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  • Python bindings for C++ code using OpenCV giving segmentation fault

    - by lightalchemist
    I'm trying to write a python wrapper for some C++ code that make use of OpenCV but I'm having difficulties returning the result, which is a OpenCV C++ Mat object, to the python interpreter. I've looked at OpenCV's source and found the file cv2.cpp which has conversions functions to perform conversions to and fro between PyObject* and OpenCV's Mat. I made use of those conversions functions but got a segmentation fault when I tried to use them. I basically need some suggestions/sample code/online references on how to interface python and C++ code that make use of OpenCV, specifically with the ability to return OpenCV's C++ Mat to the python interpreter or perhaps suggestions on how/where to start investigating the cause of the segmentation fault. Currently I'm using Boost Python to wrap the code. Thanks in advance to any replies. The relevant code: // This is the function that is giving the segmentation fault. PyObject* ABC::doSomething(PyObject* image) { Mat m; pyopencv_to(image, m); // This line gives segmentation fault. // Some code to create cppObj from CPP library that uses OpenCV cv::Mat processedImage = cppObj->align(m); return pyopencv_from(processedImage); } The conversion functions taken from OpenCV's source follows. The conversion code gives segmentation fault at the commented line with "if (!PyArray_Check(o)) ...". static int pyopencv_to(const PyObject* o, Mat& m, const char* name = "<unknown>", bool allowND=true) { if(!o || o == Py_None) { if( !m.data ) m.allocator = &g_numpyAllocator; return true; } if( !PyArray_Check(o) ) // Segmentation fault inside PyArray_Check(o) { failmsg("%s is not a numpy array", name); return false; } int typenum = PyArray_TYPE(o); int type = typenum == NPY_UBYTE ? CV_8U : typenum == NPY_BYTE ? CV_8S : typenum == NPY_USHORT ? CV_16U : typenum == NPY_SHORT ? CV_16S : typenum == NPY_INT || typenum == NPY_LONG ? CV_32S : typenum == NPY_FLOAT ? CV_32F : typenum == NPY_DOUBLE ? CV_64F : -1; if( type < 0 ) { failmsg("%s data type = %d is not supported", name, typenum); return false; } int ndims = PyArray_NDIM(o); if(ndims >= CV_MAX_DIM) { failmsg("%s dimensionality (=%d) is too high", name, ndims); return false; } int size[CV_MAX_DIM+1]; size_t step[CV_MAX_DIM+1], elemsize = CV_ELEM_SIZE1(type); const npy_intp* _sizes = PyArray_DIMS(o); const npy_intp* _strides = PyArray_STRIDES(o); bool transposed = false; for(int i = 0; i < ndims; i++) { size[i] = (int)_sizes[i]; step[i] = (size_t)_strides[i]; } if( ndims == 0 || step[ndims-1] > elemsize ) { size[ndims] = 1; step[ndims] = elemsize; ndims++; } if( ndims >= 2 && step[0] < step[1] ) { std::swap(size[0], size[1]); std::swap(step[0], step[1]); transposed = true; } if( ndims == 3 && size[2] <= CV_CN_MAX && step[1] == elemsize*size[2] ) { ndims--; type |= CV_MAKETYPE(0, size[2]); } if( ndims > 2 && !allowND ) { failmsg("%s has more than 2 dimensions", name); return false; } m = Mat(ndims, size, type, PyArray_DATA(o), step); if( m.data ) { m.refcount = refcountFromPyObject(o); m.addref(); // protect the original numpy array from deallocation // (since Mat destructor will decrement the reference counter) }; m.allocator = &g_numpyAllocator; if( transposed ) { Mat tmp; tmp.allocator = &g_numpyAllocator; transpose(m, tmp); m = tmp; } return true; } static PyObject* pyopencv_from(const Mat& m) { if( !m.data ) Py_RETURN_NONE; Mat temp, *p = (Mat*)&m; if(!p->refcount || p->allocator != &g_numpyAllocator) { temp.allocator = &g_numpyAllocator; m.copyTo(temp); p = &temp; } p->addref(); return pyObjectFromRefcount(p->refcount); } My python test program: import pysomemodule # My python wrapped library. import cv2 def main(): myobj = pysomemodule.ABC("faces.train") # Create python object. This works. image = cv2.imread('61.jpg') processedImage = myobj.doSomething(image) cv2.imshow("test", processedImage) cv2.waitKey() if __name__ == "__main__": main()

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  • C++ Mutexes and STL Lists Across Subclasses

    - by Genesis
    I am currently writing a multi-threaded C++ server using Poco and am now at the point where I need to be keeping information on which users are connected, how many connections each of them have, and given it is a proxy server, where each of those connections are proxying through to. For this purpose I have created a ServerStats class which holds an STL list of ServerUser objects. The ServerStats class includes functions which can add and remove objects from the list as well as find a user in the list an return a pointer to them so I can access member functions within any given ServerUser object in the list. The ServerUser class contains an STL list of ServerConnection objects and much like the ServerStats class it contains functions to add, remove and find elements within this list. Now all of the above is working but I am now trying to make it threadsafe. I have defined a Poco::FastMutex within the ServerStats class and can lock/unlock this in the appropriate places so that STL containers are not modified at the same time as being searched for example. I am however having an issue setting up mutexes within the ServerUser class and am getting the following compiler error: /root/poco/Foundation/include/Poco/Mutex.h: In copy constructor âServerUser::ServerUser(const ServerUser&)â: src/SocksServer.cpp:185: instantiated from âvoid __gnu_cxx::new_allocator<_Tp::construct(_Tp*, const _Tp&) [with _Tp = ServerUser]â /usr/include/c++/4.4/bits/stl_list.h:464: instantiated from âstd::_List_node<_Tp* std::list<_Tp, _Alloc::_M_create_node(const _Tp&) [with _Tp = ServerUser, _Alloc = std::allocator]â /usr/include/c++/4.4/bits/stl_list.h:1407: instantiated from âvoid std::list<_Tp, _Alloc::_M_insert(std::_List_iterator<_Tp, const _Tp&) [with _Tp = ServerUser, _Alloc = std::allocator]â /usr/include/c++/4.4/bits/stl_list.h:920: instantiated from âvoid std::list<_Tp, _Alloc::push_back(const _Tp&) [with _Tp = ServerUser, _Alloc = std::allocator]â src/SocksServer.cpp:301: instantiated from here /root/poco/Foundation/include/Poco/Mutex.h:164: error: âPoco::FastMutex::FastMutex(const Poco::FastMutex&)â is private src/SocksServer.cpp:185: error: within this context In file included from /usr/include/c++/4.4/x86_64-linux-gnu/bits/c++allocator.h:34, from /usr/include/c++/4.4/bits/allocator.h:48, from /usr/include/c++/4.4/string:43, from /root/poco/Foundation/include/Poco/Bugcheck.h:44, from /root/poco/Foundation/include/Poco/Foundation.h:147, from /root/poco/Net/include/Poco/Net/Net.h:45, from /root/poco/Net/include/Poco/Net/TCPServerParams.h:43, from src/SocksServer.cpp:1: /usr/include/c++/4.4/ext/new_allocator.h: In member function âvoid __gnu_cxx::new_allocator<_Tp::construct(_Tp*, const _Tp&) [with _Tp = ServerUser]â: /usr/include/c++/4.4/ext/new_allocator.h:105: note: synthesized method âServerUser::ServerUser(const ServerUser&)â first required here src/SocksServer.cpp: At global scope: src/SocksServer.cpp:118: warning: âstd::string getWord(std::string)â defined but not used make: * [/root/poco/SocksServer/obj/Linux/x86_64/debug_shared/SocksServer.o] Error 1 The code for the ServerStats, ServerUser and ServerConnection classes is below: class ServerConnection { public: bool continue_connection; int bytes_in; int bytes_out; string source_address; string destination_address; ServerConnection() { continue_connection = true; } ~ServerConnection() { } }; class ServerUser { public: string username; int connection_count; string client_ip; ServerUser() { } ~ServerUser() { } ServerConnection* addConnection(string source_address, string destination_address) { //FastMutex::ScopedLock lock(_connection_mutex); ServerConnection connection; connection.source_address = source_address; connection.destination_address = destination_address; client_ip = getWord(source_address, ":"); _connections.push_back(connection); connection_count++; return &_connections.back(); } void removeConnection(string source_address) { //FastMutex::ScopedLock lock(_connection_mutex); for(list<ServerConnection>::iterator it = _connections.begin(); it != _connections.end(); it++) { if(it->source_address == source_address) { it = _connections.erase(it); connection_count--; } } } void disconnect() { //FastMutex::ScopedLock lock(_connection_mutex); for(list<ServerConnection>::iterator it = _connections.begin(); it != _connections.end(); it++) { it->continue_connection = false; } } list<ServerConnection>* getConnections() { return &_connections; } private: list<ServerConnection> _connections; //UNCOMMENTING THIS LINE BREAKS IT: //mutable FastMutex _connection_mutex; }; class ServerStats { public: int current_users; ServerStats() { current_users = 0; } ~ServerStats() { } ServerUser* addUser(string username) { FastMutex::ScopedLock lock(_user_mutex); for(list<ServerUser>::iterator it = _users.begin(); it != _users.end(); it++) { if(it->username == username) { return &(*it); } } ServerUser newUser; newUser.username = username; _users.push_back(newUser); current_users++; return &_users.back(); } void removeUser(string username) { FastMutex::ScopedLock lock(_user_mutex); for(list<ServerUser>::iterator it = _users.begin(); it != _users.end(); it++) { if(it->username == username) { _users.erase(it); current_users--; break; } } } ServerUser* getUser(string username) { FastMutex::ScopedLock lock(_user_mutex); for(list<ServerUser>::iterator it = _users.begin(); it != _users.end(); it++) { if(it->username == username) { return &(*it); } } return NULL; } private: list<ServerUser> _users; mutable FastMutex _user_mutex; }; Now I have never used C++ for a project of this size or mutexes for that matter so go easy please :) Firstly, can anyone tell me why the above is causing a compiler error? Secondly, can anyone suggest a better way of storing the information I require? Bear in mind that I need to update this info whenever connections come or go and it needs to be global to the whole server.

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  • How to change Matlab program for solving equation with finite element method?

    - by DSblizzard
    I don't know is this question more related to mathematics or programming and I'm absolute newbie in Matlab. Program FEM_50 applies the finite element method to Laplace's equation -Uxx(x, y) - Uyy(x, y) = F(x, y) in Omega. How to change it to apply FEM to equation -Uxx(x, y) - Uyy(x, y) + U(x, y) = F(x, y)? At this page: http://sc.fsu.edu/~burkardt/m_src/fem_50/fem_50.html additional code files in case you need them. function fem_50 ( ) %% FEM_50 applies the finite element method to Laplace's equation. % % Discussion: % % FEM_50 is a set of MATLAB routines to apply the finite % element method to solving Laplace's equation in an arbitrary % region, using about 50 lines of MATLAB code. % % FEM_50 is partly a demonstration, to show how little it % takes to implement the finite element method (at least using % every possible MATLAB shortcut.) The user supplies datafiles % that specify the geometry of the region and its arrangement % into triangular and quadrilateral elements, and the location % and type of the boundary conditions, which can be any mixture % of Neumann and Dirichlet. % % The unknown state variable U(x,y) is assumed to satisfy % Laplace's equation: % -Uxx(x,y) - Uyy(x,y) = F(x,y) in Omega % with Dirichlet boundary conditions % U(x,y) = U_D(x,y) on Gamma_D % and Neumann boundary conditions on the outward normal derivative: % Un(x,y) = G(x,y) on Gamma_N % If Gamma designates the boundary of the region Omega, % then we presume that % Gamma = Gamma_D + Gamma_N % but the user is free to determine which boundary conditions to % apply. Note, however, that the problem will generally be singular % unless at least one Dirichlet boundary condition is specified. % % The code uses piecewise linear basis functions for triangular elements, % and piecewise isoparametric bilinear basis functions for quadrilateral % elements. % % The user is required to supply a number of data files and MATLAB % functions that specify the location of nodes, the grouping of nodes % into elements, the location and value of boundary conditions, and % the right hand side function in Laplace's equation. Note that the % fact that the geometry is completely up to the user means that % just about any two dimensional region can be handled, with arbitrary % shape, including holes and islands. % clear % % Read the nodal coordinate data file. % load coordinates.dat; % % Read the triangular element data file. % load elements3.dat; % % Read the quadrilateral element data file. % load elements4.dat; % % Read the Neumann boundary condition data file. % I THINK the purpose of the EVAL command is to create an empty NEUMANN array % if no Neumann file is found. % eval ( 'load neumann.dat;', 'neumann=[];' ); % % Read the Dirichlet boundary condition data file. % load dirichlet.dat; A = sparse ( size(coordinates,1), size(coordinates,1) ); b = sparse ( size(coordinates,1), 1 ); % % Assembly. % for j = 1 : size(elements3,1) A(elements3(j,:),elements3(j,:)) = A(elements3(j,:),elements3(j,:)) ... + stima3(coordinates(elements3(j,:),:)); end for j = 1 : size(elements4,1) A(elements4(j,:),elements4(j,:)) = A(elements4(j,:),elements4(j,:)) ... + stima4(coordinates(elements4(j,:),:)); end % % Volume Forces. % for j = 1 : size(elements3,1) b(elements3(j,:)) = b(elements3(j,:)) ... + det( [1,1,1; coordinates(elements3(j,:),:)'] ) * ... f(sum(coordinates(elements3(j,:),:))/3)/6; end for j = 1 : size(elements4,1) b(elements4(j,:)) = b(elements4(j,:)) ... + det([1,1,1; coordinates(elements4(j,1:3),:)'] ) * ... f(sum(coordinates(elements4(j,:),:))/4)/4; end % % Neumann conditions. % if ( ~isempty(neumann) ) for j = 1 : size(neumann,1) b(neumann(j,:)) = b(neumann(j,:)) + ... norm(coordinates(neumann(j,1),:) - coordinates(neumann(j,2),:)) * ... g(sum(coordinates(neumann(j,:),:))/2)/2; end end % % Determine which nodes are associated with Dirichlet conditions. % Assign the corresponding entries of U, and adjust the right hand side. % u = sparse ( size(coordinates,1), 1 ); BoundNodes = unique ( dirichlet ); u(BoundNodes) = u_d ( coordinates(BoundNodes,:) ); b = b - A * u; % % Compute the solution by solving A * U = B for the remaining unknown values of U. % FreeNodes = setdiff ( 1:size(coordinates,1), BoundNodes ); u(FreeNodes) = A(FreeNodes,FreeNodes) \ b(FreeNodes); % % Graphic representation. % show ( elements3, elements4, coordinates, full ( u ) ); return end

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  • Custom styled select box

    - by Ivan
    Hi to all am trying to use javascript for custom styled select boxes from www.gerrendesign.com/entry_images/selectboxdemo.zip and as I have plenty entries inside one of select box I need to make but am stuck in creation of scrolling function. As this select boxes are compatible with almost all older and new browsers. I need only suggestion or solution how to add scroll in this linked/attached files above - if select box is populated with plenty of entries (example cities, states, or exchange rates...) Am stuck here... Thanks for your cooperation Ivan THIS IS CODE: $(document).ready(function(){ // first locate all of the select tags on the page and hide them $("select.changeMe").css('display','none'); //now, for each select box, run this function $("select.changeMe").each(function(){ var curSel = $(this); // get the CSS width from the original select box var gddWidth = $(curSel).css('width'); var gddWidthL = gddWidth.slice(0,-2); var gddWidth2 = gddWidthL - 28; var gddWidth3 = gddWidthL - 16; // build the new div structure var gddTop = '<div style="width:' + gddWidthL + 'px" class="selectME" tabindex="0"><div class="cornerstop"><div><div></div></div></div><div class="middle"><div><div><div>'; //get the default selected option var whatSelected = $(curSel).children('option:selected').text(); //write the default var gddFirst = '<div class="first"><span class="selectME gselected" style="width:'+ gddWidth2 + 'px;">'+ whatSelected +'</span><span id="arrowImg"></span><div class="clears"></div></div><ul class="selectME">'; // create a new array of div options from the original's options var addItems = new Array(); $(curSel).children('option').each( function() { var text = $(this).text(); var selVal = $(this).attr('value'); var before = '<li style="width:' + gddWidthL + 'px;"><a href="#" rel="' + selVal + '" tabindex="0" style="width:' + gddWidth3 + 'px;">'; var after = '</a></li>'; addItems.push(before + text + after); }); //hide the default from the list of options var removeFirst = addItems.shift(); // create the end of the div selectbox and close everything off var gddBottom ='</ul></div></div></div></div><div class="cornersbottom"><div><div></div></div></div></div>' //write everything after each selectbox var GDD = gddTop + gddFirst + addItems.join('') + gddBottom; $(curSel).after(GDD); //this var selects the div select box directly after each of the origials var nGDD = $(curSel).next('div.selectME'); $(nGDD).find('li:first').addClass("first"); $(nGDD).find('li:last').addClass('last'); //handle the on click functions - push results back to old text box $(nGDD).click( function(e) { var myTarA = $(e.target).attr('rel'); var myTarT = $(e.target).text(); var myTar = $(e.target); //if closed, then open if( $(nGDD).find('li').css('display') == 'none') { //this next line closes any other selectboxes that might be open $('div.selectME').find('li').css('display','none'); $(nGDD).find('li').css('display','block'); //if user clicks off of the div select box, then shut the whole thing down $(document.window || 'body').click( function(f) { var myTar2 = $(f.target); if (myTar2 !== nGDD) {$(nGDD).find('li').css('display','none');} }); return false; } else { if (myTarA == null){ $(nGDD).find('li').css('display','none'); return false; } else { //set the value of the old select box $(curSel).val(myTarA); //set the text of the new one $(nGDD).find('span.gselected').text(myTarT); $(nGDD).find('li').css('display','none'); return false; } } //handle the tab index functions }).focus( function(e) { $(nGDD).find('li:first').addClass('currentDD'); $(nGDD).find('li:last').addClass('lastDD'); function checkKey(e){ //on keypress handle functions function moveDown() { var current = $(nGDD).find('.currentDD:first'); var next = $(nGDD).find('.currentDD').next(); if ($(current).is('.lastDD')){ return false; } else { $(next).addClass('currentDD'); $(current).removeClass('currentDD'); } } function moveUp() { var current = $(nGDD).find('.currentDD:first'); var prev = $(nGDD).find('.currentDD').prev(); if ($(current).is('.first')){ return false; } else { $(prev).addClass('currentDD'); $(current).removeClass('currentDD'); } } var curText = $(nGDD).find('.currentDD:first').text(); var curVal = $(nGDD).find('.currentDD:first a').attr('rel'); switch (e.keyCode) { case 40: $(curSel).val(curVal); $(nGDD).find('span.gselected').text(curText); moveDown(); return false; break; case 38: $(curSel).val(curVal); $(nGDD).find('span.gselected').text(curText); moveUp(); return false; break; case 13: $(nGDD).find('li').css('display','none'); } } $(document).keydown(checkKey); }).blur( function() { $(document).unbind('keydown'); }); }); });

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  • Marking multi-level nested forms as "dirty" in Rails

    - by Charles Kihe
    I have a three-level multi-nested form in Rails. The setup is like this: Projects have many Milestones, and Milestones have many Notes. The goal is to have everything editable within the page with JavaScript, where we can add multiple new Milestones to a Project within the page, and add new Notes to new and existing Milestones. Everything works as expected, except that when I add new notes to an existing Milestone (new Milestones work fine when adding notes to them), the new notes won't save unless I edit any of the fields that actually belong to the Milestone to mark the form "dirty"/edited. Is there a way to flag the Milestone so that the new Notes that have been added will save? Edit: sorry, it's hard to paste in all of the code because there's so many parts, but here goes: Models class Project < ActiveRecord::Base has_many :notes, :dependent => :destroy has_many :milestones, :dependent => :destroy accepts_nested_attributes_for :milestones, :allow_destroy => true accepts_nested_attributes_for :notes, :allow_destroy => true, :reject_if => proc { |attributes| attributes['content'].blank? } end class Milestone < ActiveRecord::Base belongs_to :project has_many :notes, :dependent => :destroy accepts_nested_attributes_for :notes, :allow_destroy => true, :allow_destroy => true, :reject_if => proc { |attributes| attributes['content'].blank? } end class Note < ActiveRecord::Base belongs_to :milestone belongs_to :project scope :newest, lambda { |*args| order('created_at DESC').limit(*args.first || 3) } end I'm using an jQuery-based, unobtrusive version of Ryan Bates' combo helper/JS code to get this done. Application Helper def add_fields_for_association(f, association, partial) new_object = f.object.class.reflect_on_association(association).klass.new fields = f.fields_for(association, new_object, :child_index => "new_#{association}") do |builder| render(partial, :f => builder) end end I render the form for the association in a hidden div, and then use the following JavaScript to find it and add it as needed. JavaScript function addFields(link, association, content, func) { var newID = new Date().getTime(); var regexp = new RegExp("new_" + association, "g"); var form = content.replace(regexp, newID); var link = $(link).parent().next().before(form).prev(); if (func) { func.call(); } return link; } I'm guessing the only other relevant piece of code that I can think of would be the create method in the NotesController: def create respond_with(@note = @owner.notes.create(params[:note])) do |format| format.js { render :json => @owner.notes.newest(3).all.to_json } format.html { redirect_to((@milestone ? [@project, @milestone, @note] : [@project, @note]), :notice => 'Note was successfully created.') } end end The @owner ivar is created in the following before filter: def load_milestone @milestone = @project.milestones.find(params[:milestone_id]) if params[:milestone_id] end def determine_owner @owner = load_milestone @owner ||= @project end Thing is, all this seems to work fine, except when I'm adding new notes to existing milestones. The milestone has to be "touched" in order for new notes to save, or else Rails won't pay attention.

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  • Where is the virtual function call overhead?

    - by Semen Semenych
    Hello everybody, I'm trying to benchmark the difference between a function pointer call and a virtual function call. To do this, I have written two pieces of code, that do the same mathematical computation over an array. One variant uses an array of pointers to functions and calls those in a loop. The other variant uses an array of pointers to a base class and calls its virtual function, which is overloaded in the derived classes to do absolutely the same thing as the functions in the first variant. Then I print the time elapsed and use a simple shell script to run the benchmark many times and compute the average run time. Here is the code: #include <iostream> #include <cstdlib> #include <ctime> #include <cmath> using namespace std; long long timespecDiff(struct timespec *timeA_p, struct timespec *timeB_p) { return ((timeA_p->tv_sec * 1000000000) + timeA_p->tv_nsec) - ((timeB_p->tv_sec * 1000000000) + timeB_p->tv_nsec); } void function_not( double *d ) { *d = sin(*d); } void function_and( double *d ) { *d = cos(*d); } void function_or( double *d ) { *d = tan(*d); } void function_xor( double *d ) { *d = sqrt(*d); } void ( * const function_table[4] )( double* ) = { &function_not, &function_and, &function_or, &function_xor }; int main(void) { srand(time(0)); void ( * index_array[100000] )( double * ); double array[100000]; for ( long int i = 0; i < 100000; ++i ) { index_array[i] = function_table[ rand() % 4 ]; array[i] = ( double )( rand() / 1000 ); } struct timespec start, end; clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start); for ( long int i = 0; i < 100000; ++i ) { index_array[i]( &array[i] ); } clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end); unsigned long long time_elapsed = timespecDiff(&end, &start); cout << time_elapsed / 1000000000.0 << endl; } and here is the virtual function variant: #include <iostream> #include <cstdlib> #include <ctime> #include <cmath> using namespace std; long long timespecDiff(struct timespec *timeA_p, struct timespec *timeB_p) { return ((timeA_p->tv_sec * 1000000000) + timeA_p->tv_nsec) - ((timeB_p->tv_sec * 1000000000) + timeB_p->tv_nsec); } class A { public: virtual void calculate( double *i ) = 0; }; class A1 : public A { public: void calculate( double *i ) { *i = sin(*i); } }; class A2 : public A { public: void calculate( double *i ) { *i = cos(*i); } }; class A3 : public A { public: void calculate( double *i ) { *i = tan(*i); } }; class A4 : public A { public: void calculate( double *i ) { *i = sqrt(*i); } }; int main(void) { srand(time(0)); A *base[100000]; double array[100000]; for ( long int i = 0; i < 100000; ++i ) { array[i] = ( double )( rand() / 1000 ); switch ( rand() % 4 ) { case 0: base[i] = new A1(); break; case 1: base[i] = new A2(); break; case 2: base[i] = new A3(); break; case 3: base[i] = new A4(); break; } } struct timespec start, end; clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &start); for ( int i = 0; i < 100000; ++i ) { base[i]->calculate( &array[i] ); } clock_gettime(CLOCK_PROCESS_CPUTIME_ID, &end); unsigned long long time_elapsed = timespecDiff(&end, &start); cout << time_elapsed / 1000000000.0 << endl; } My system is LInux, Fedora 13, gcc 4.4.2. The code is compiled it with g++ -O3. The first one is test1, the second is test2. Now I see this in console: [Ignat@localhost circuit_testing]$ ./test2 && ./test2 0.0153142 0.0153166 Well, more or less, I think. And then, this: [Ignat@localhost circuit_testing]$ ./test2 && ./test2 0.01531 0.0152476 Where are the 25% which should be visible? How can the first executable be even slower than the second one? I'm asking this because I'm doing a project which involves calling a lot of small functions in a row like this in order to compute the values of an array, and the code I've inherited does a very complex manipulation to avoid the virtual function call overhead. Now where is this famous call overhead?

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  • linux thread synchronization

    - by johnnycrash
    I am new to linux and linux threads. I have spent some time googling to try to understand the differences between all the functions available for thread synchronization. I still have some questions. I have found all of these different types of synchronizations, each with a number of functions for locking, unlocking, testing the lock, etc. gcc atomic operations futexes mutexes spinlocks seqlocks rculocks conditions semaphores My current (but probably flawed) understanding is this: semaphores are process wide, involve the filesystem (virtually I assume), and are probably the slowest. Futexes might be the base locking mechanism used by mutexes, spinlocks, seqlocks, and rculocks. Futexes might be faster than the locking mechanisms that are based on them. Spinlocks dont block and thus avoid context swtiches. However they avoid the context switch at the expense of consuming all the cycles on a CPU until the lock is released (spinning). They should only should be used on multi processor systems for obvious reasons. Never sleep in a spinlock. The seq lock just tells you when you finished your work if a writer changed the data the work was based on. You have to go back and repeat the work in this case. Atomic operations are the fastest synch call, and probably are used in all the above locking mechanisms. You do not want to use atomic operations on all the fields in your shared data. You want to use a lock (mutex, futex, spin, seq, rcu) or a single atomic opertation on a lock flag when you are accessing multiple data fields. My questions go like this: Am I right so far with my assumptions? Does anyone know the cpu cycle cost of the various options? I am adding parallelism to the app so we can get better wall time response at the expense of running fewer app instances per box. Performances is the utmost consideration. I don't want to consume cpu with context switching, spinning, or lots of extra cpu cycles to read and write shared memory. I am absolutely concerned with number of cpu cycles consumed. Which (if any) of the locks prevent interruption of a thread by the scheduler or interrupt...or am I just an idiot and all synchonization mechanisms do this. What kinds of interruption are prevented? Can I block all threads or threads just on the locking thread's CPU? This question stems from my fear of interrupting a thread holding a lock for a very commonly used function. I expect that the scheduler might schedule any number of other workers who will likely run into this function and then block because it was locked. A lot of context switching would be wasted until the thread with the lock gets rescheduled and finishes. I can re-write this function to minimize lock time, but still it is so commonly called I would like to use a lock that prevents interruption...across all processors. I am writing user code...so I get software interrupts, not hardware ones...right? I should stay away from any functions (spin/seq locks) that have the word "irq" in them. Which locks are for writing kernel or driver code and which are meant for user mode? Does anyone think using an atomic operation to have multiple threads move through a linked list is nuts? I am thinking to atomicly change the current item pointer to the next item in the list. If the attempt works, then the thread can safely use the data the current item pointed to before it was moved. Other threads would now be moved along the list. futexes? Any reason to use them instead of mutexes? Is there a better way than using a condition to sleep a thread when there is no work? When using gcc atomic ops, specifically the test_and_set, can I get a performance increase by doing a non atomic test first and then using test_and_set to confirm? *I know this will be case specific, so here is the case. There is a large collection of work items, say thousands. Each work item has a flag that is initialized to 0. When a thread has exclusive access to the work item, the flag will be one. There will be lots of worker threads. Any time a thread is looking for work, they can non atomicly test for 1. If they read a 1, we know for certain that the work is unavailable. If they read a zero, they need to perform the atomic test_and_set to confirm. So if the atomic test_and_set is 500 cpu cycles because it is disabling pipelining, causes cpu's to communicate and L2 caches to flush/fill .... and a simple test is 1 cycle .... then as long as I had a better ratio of 500 to 1 when it came to stumbling upon already completed work items....this would be a win.* I hope to use mutexes or spinlocks to sparilngly protect sections of code that I want only one thread on the SYSTEM (not jsut the CPU) to access at a time. I hope to sparingly use gcc atomic ops to select work and minimize use of mutexes and spinlocks. For instance: a flag in a work item can be checked to see if a thread has worked it (0=no, 1=yes or in progress). A simple test_and_set tells the thread if it has work or needs to move on. I hope to use conditions to wake up threads when there is work. Thanks!

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  • validating cascading dropdownlist

    - by shruti
    i am working on MVC.Net. in that i have used cascading dropdownlist. I want to do validations for blank field. the view page coding is: Select Category: <%= Html.DropDownList("Makes", ViewData["Makes"] as SelectList,"Select Category")% Select Subcategory: <%= Html.CascadingDropDownList("Models", "Makes")% the code on controller: public ActionResult AddSubCategoryPage() { var makeList = new SelectList(entityObj.Category.ToList(), "Category_id", "Category_name"); ViewData["Makes"] = makeList; // Create Models view data var modelList = new CascadingSelectList(entityObj.Subcategory1.ToList(), "Category_id", "Subcategory_id", "Subcategory_name"); ViewData["Models"] = modelList; return View("AddSubCategoryPage"); } and for that i have made one class: public static class JavaScriptExtensions { public static string CascadingDropDownList(this HtmlHelper helper, string name, string associatedDropDownList) { var sb = new StringBuilder(); // render select tag sb.AppendFormat("<select name='{0}' id='{0}'></select>", name); sb.AppendLine(); // render data array sb.AppendLine("<script type='text/javascript'>"); var data = (CascadingSelectList)helper.ViewDataContainer.ViewData[name]; var listItems = data.GetListItems(); var colArray = new List<string>(); foreach (var item in listItems) colArray.Add(String.Format("{{key:'{0}',value:'{1}',text:'{2}'}}", item.Key, item.Value, item.Text)); var jsArray = String.Join(",", colArray.ToArray()); sb.AppendFormat("$get('{0}').allOptions=[{1}];", name, jsArray); sb.AppendLine(); sb.AppendFormat("$addHandler($get('{0}'), 'change', Function.createCallback(bindDropDownList, $get('{1}')));", associatedDropDownList, name); sb.AppendLine(); sb.AppendLine("</script>"); return sb.ToString(); } } public class CascadingSelectList { private IEnumerable _items; private string _dataKeyField; private string _dataValueField; private string _dataTextField; public CascadingSelectList(IEnumerable items, string dataKeyField, string dataValueField, string dataTextField) { _items = items; _dataKeyField = dataKeyField; _dataValueField = dataValueField; _dataTextField = dataTextField; } public List<CascadingListItem> GetListItems() { var listItems = new List<CascadingListItem>(); foreach (var item in _items) { var key = DataBinder.GetPropertyValue(item, _dataKeyField).ToString(); var value = DataBinder.GetPropertyValue(item, _dataValueField).ToString(); var text = DataBinder.GetPropertyValue(item, _dataTextField).ToString(); listItems.Add(new CascadingListItem(key, value, text)); } return listItems; } } public class CascadingListItem { public CascadingListItem(string key, string value, string text) { this.Key = key; this.Value = value; this.Text = text; } public string Key { get; set; } public string Value { get; set; } public string Text { get; set; } } but when i run the aaplication it gives me following error: Server Error in '/' Application. The parameters dictionary contains a null entry for parameter 'Models' of non-nullable type 'System.Int32' for method 'System.Web.Mvc.ActionResult AddSubCategoryPage(Int32, System.String, System.String)' in 'CMS.Controllers.HomeController'. An optional parameter must be a reference type, a nullable type, or be declared as an optional parameter. Parameter name: parameters . plz help me.

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  • uploading zip files in codeigniter won't work

    - by krike
    I have created a helper that requires some parameters and should upload a file, the function works for images however not for zip files. I searched on google and even added a MY_upload.php - http://codeigniter.com/bug_tracker/bug/6780/ however I still have the problem so I used print_r to display the array of the uploaded files, the image is fine however the zip array is empty: Array ( [file_name] => [file_type] => [file_path] => [full_path] => [raw_name] => [orig_name] => [file_ext] => [file_size] => [is_image] => [image_width] => [image_height] => [image_type] => [image_size_str] => ) Array ( [file_name] => 2385b959279b5e3cd451fee54273512c.png [file_type] => image/png [file_path] => I:/wamp/www/e-commerce/sources/images/ [full_path] => I:/wamp/www/e-commerce/sources/images/2385b959279b5e3cd451fee54273512c.png [raw_name] => 2385b959279b5e3cd451fee54273512c [orig_name] => 1269770869_Art_Artdesigner.lv_.png [file_ext] => .png [file_size] => 15.43 [is_image] => 1 [image_width] => 113 [image_height] => 128 [image_type] => png [image_size_str] => width="113" height="128" ) this is the function helper function multiple_upload($name = 'userfile', $upload_dir = 'sources/images/', $allowed_types = 'gif|jpg|jpeg|jpe|png', $size) { $CI =& get_instance(); $config['upload_path'] = realpath($upload_dir); $config['allowed_types'] = $allowed_types; $config['max_size'] = $size; $config['overwrite'] = FALSE; $config['encrypt_name'] = TRUE; $ffiles = $CI->upload->data(); echo "<pre>"; print_r($ffiles); echo "</pre>"; $CI->upload->initialize($config); $errors = FALSE; if(!$CI->upload->do_upload($name))://I believe this is causing the problem but I'm new to codeigniter so no idea where to look for errors $errors = TRUE; else: // Build a file array from all uploaded files $files = $CI->upload->data(); endif; // There was errors, we have to delete the uploaded files if($errors): @unlink($files['full_path']); return false; else: return $files; endif; }//end of multiple_upload() and this is the code in my controller if(!$s_thumb = multiple_upload('small_thumb', 'sources/images/', 'gif|jpg|jpeg|jpe|png', 1024)): //http://www.matisse.net/bitcalc/ $data['feedback'] = '<div class="error">Could not upload the small thumbnail!</div>'; $error = TRUE; endif; if(!$main_file = multiple_upload('main_file', 'sources/items/', 'zip', 307200)): $data['feedback'] = '<div class="error">Could not upload the main file!</div>'; $error = TRUE; endif;

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  • Magento Admin Custom Sales Report

    - by Ela
    Hi, I have to develop a module to export collection of product,order,customer combined attributes. So i thought rather than modifying the core sales report for this purpose better to do a custom functionality. These are the steps that i did but i am not able to produce it. Used magento 1.4.1 version for this. Under /var/www/magento141/app/code/core/Mage/Reports/etc/adminhtml.xml Added these lines for menus. <ereaders translate="title" module="reports"> <title>EReader Sales Report</title> <children> <ereaders translate="title" module="reports"> <title>Sales Report</title> <action>adminhtml/report_sales/ereaders</action> </ereaders> </children> </ereaders> Under /var/www/magento141/app/design/adminhtml/default/default/layout/sales.xml Added these lines for filter condition. <adminhtml_report_sales_ereaders> <update handle="report_sales"/> <reference name="content"> <block type="adminhtml/report_sales_sales" template="report/grid/container.phtml" name="sales.report.grid.container"> <block type="adminhtml/store_switcher" template="report/store/switcher/enhanced.phtml" name="store.switcher"> <action method="setStoreVarName"><var_name>store_ids</var_name></action> </block> <block type="sales/adminhtml_report_filter_form_order" name="grid.filter.form"> ---- </block> </block> </reference> </adminhtml_report_sales_ereaders> And then copied the needed block,model files from sales and renamed all of them into ereaders under /var/www/magento141/app/code/core/Mage/Adminhtml/. Then placed action for ereaders under /var/www/magento141/app/code/core/Mage/Adminhtml/controllers/Report/SalesController.php public function ereadersAction() { $this->_title($this->__('Reports'))->_title($this->__('Sales'))->_title($this->__('EReaders Sales')); $this->_showLastExecutionTime(Mage_Reports_Model_Flag::REPORT_ORDER_FLAG_CODE, 'ereaders'); $this->_initAction() ->_setActiveMenu('report/sales/ereaders') ->_addBreadcrumb(Mage::helper('adminhtml')->__('EReaders Sales Report'), Mage::helper('adminhtml')->__('EReaders Sales Report')); $gridBlock = $this->getLayout()->getBlock('report_sales_ereaders.grid'); $filterFormBlock = $this->getLayout()->getBlock('grid.filter.form'); $this->_initReportAction(array( $gridBlock, $filterFormBlock )); $this->renderLayout(); } Here when i use var_dump == //var_dump($this-getLayout()-getBlock('report_sales_ereaders.grid')); am getting bool(false) only. It does not call the ereaders grid, instead of its still loading blocks and grids from Sales only. I searched most of the files related to report, am not still able to find out the problem. Hope many of you gone through these sort of issues, please can anyone tell me where am making mistake or missing something.

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  • (C++) Linking with namespaces causes duplicate symbol error

    - by user577072
    Hello. For the past few days, I have been trying to figure out how to link the files for a CLI gaming project I have been working on. There are two halves of the project, the Client and the Server code. The client needs two libraries I've made. The first is a general purpose game board. This is split between GameEngine.h and GameEngine.cpp. The header file looks something like this namespace gfdGaming { // struct sqr_size { // Index x; // Index y; // }; typedef struct { Index x, y; } sqr_size; const sqr_size sPos = {1, 1}; sqr_size sqr(Index x, Index y); sqr_size ePos; class board { // Prototypes / declarations for the class } } And the CPP file is just giving everything content #include "GameEngine.h" type gfdGaming::board::functions The client also has game-specific code (in this case, TicTacToe) split into declarations and definitions (TTT.h, Client.cpp). TTT.h is basically #include "GameEngine.h" #define TTTtar "localhost" #define TTTport 2886 using namespace gfdGaming; void* turnHandler(void*); namespace nsTicTacToe { GFDCON gfd; const char X = 'X'; const char O = 'O'; string MPhostname, mySID; board TTTboard; bool PlayerIsX = true, isMyTurn; char Player = X, Player2 = O; int recon(string* datHolder = NULL, bool force = false); void initMP(bool create = false, string hn = TTTtar); void init(); bool isTie(); int turnPlayer(Index loc, char lSym = Player); bool checkWin(char sym = Player); int mainloop(); int mainloopMP(); }; // NS I made the decision to put this in a namespace to group it instead of a class because there are some parts that would not work well in OOP, and it's much easier to implement later on. I have had trouble linking the client in the past, but this setup seems to work. My server is also split into two files, Server.h and Server.cpp. Server.h contains exactly: #include "../TicTacToe/TTT.h" // Server needs a full copy of TicTacToe code class TTTserv; struct TTTachievement_requirement { Index id; Index loc; bool inUse; }; struct TTTachievement_t { Index id; bool achieved; bool AND, inSameGame; bool inUse; bool (*lHandler)(TTTserv*); char mustBeSym; int mustBePlayer; string name, description; TTTachievement_requirement steps[safearray(8*8)]; }; class achievement_core_t : public GfdOogleTech { public: // May be shifted to private TTTachievement_t list[safearray(8*8)]; public: achievement_core_t(); int insert(string name, string d, bool samegame, bool lAnd, int lSteps[8*8], int mbP=0, char mbS=0); }; struct TTTplayer_t { Index id; bool inUse; string ip, sessionID; char sym; int desc; TTTachievement_t Ding[8*8]; }; struct TTTgame_t { TTTplayer_t Player[safearray(2)]; TTTplayer_t Spectator; achievement_core_t achievement_core; Index cTurn, players; port_t roomLoc; bool inGame, Xused, Oused, newEvent; }; class TTTserv : public gSserver { TTTgame_t Game; TTTplayer_t *cPlayer; port_t conPort; public: achievement_core_t *achiev; thread threads[8]; int parseit(string tDat, string tsIP); Index conCount; int parseit(string tDat, int tlUser, TTTplayer_t** retval); private: int parseProto(string dat, string sIP); int parseProto(string dat, int lUser); int cycleTurn(); void setup(port_t lPort = 0, bool complete = false); public: int newEvent; TTTserv(port_t tlPort = TTTport, bool tcomplete = true); TTTplayer_t* userDC(Index id, Index force = false); int sendToPlayers(string dat, bool asMSG = false); int mainLoop(volatile bool *play); }; // Other void* userHandler(void*); void* handleUser(void*); And in the CPP file I include Server.h and provide main() and the contents of all functions previously declared. Now to the problem at hand I am having issues when linking my server. More specifically, I get a duplicate symbol error for every variable in nsTicTacToe (and possibly in gfdGaming as well). Since I need the TicTacToe functions, I link Client.cpp ( without main() ) when building the server ld: duplicate symbol nsTicTacToe::PlayerIsX in Client.o and Server.o collect2: ld returned 1 exit status Command /Developer/usr/bin/g++-4.2 failed with exit code 1 It stops once a problem is encountered, but if PlayerIsX is removed / changed temporarily than another variable causes an error Essentially, I am looking for any advice on how to better organize my code to hopefully fix these errors. Disclaimers: -I apologize in advance if I provided too much or too little information, as it is my first time posting -I have tried using static and extern to fix these problems, but apparently those are not what I need Thank you to anyone who takes the time to read all of this and respond =)

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  • Java style FOR loop in a clojure interpeter ?

    - by Kevin
    I have a basic interpreter in clojure. Now i need to implement for (initialisation; finish-test; loop-update) { statements } inside my interpreter. I will attach my interpreter code I got so far. Any help is appreciated. Interpreter (declare interpret make-env) ;; (def do-trace false) ;; ;; simple utilities (def third ; return third item in a list (fn [a-list] (second (rest a-list)))) (def fourth ; return fourth item in a list (fn [a-list] (third (rest a-list)))) (def run ; make it easy to test the interpreter (fn [e] (println "Processing: " e) (println "=> " (interpret e (make-env))))) ;; for the environment (def make-env (fn [] '())) (def add-var (fn [env var val] (cons (list var val) env))) (def lookup-var (fn [env var] (cond (empty? env) 'error (= (first (first env)) var) (second (first env)) :else (lookup-var (rest env) var)))) ;; -- define numbers (def is-number? (fn [expn] (number? expn))) (def interpret-number (fn [expn env] expn)) ;; -- define symbols (def is-symbol? (fn [expn] (symbol? expn))) (def interpret-symbol (fn [expn env] (lookup-var env expn))) ;; -- define boolean (def is-boolean? (fn [expn] (or (= expn 'true) (= expn 'false)))) (def interpret-boolean (fn [expn env] expn)) ;; -- define functions (def is-function? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'lambda (first expn))))) (def interpret-function (fn [expn env] expn)) ;; -- define addition (def is-plus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '+ (first expn))))) (def interpret-plus (fn [expn env] (+ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define subtraction (def is-minus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '- (first expn))))) (def interpret-minus (fn [expn env] (- (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define multiplication (def is-times? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '* (first expn))))) (def interpret-times (fn [expn env] (* (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define division (def is-divides? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '/ (first expn))))) (def interpret-divides (fn [expn env] (/ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define equals test (def is-equals? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '= (first expn))))) (def interpret-equals (fn [expn env] (= (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define greater-than test (def is-greater-than? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '> (first expn))))) (def interpret-greater-than (fn [expn env] (> (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define not (def is-not? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'not (first expn))))) (def interpret-not (fn [expn env] (not (interpret (second expn) env)))) ;; -- define or (def is-or? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'or (first expn))))) (def interpret-or (fn [expn env] (or (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define and (def is-and? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'and (first expn))))) (def interpret-and (fn [expn env] (and (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define with (def is-with? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'with (first expn))))) (def interpret-with (fn [expn env] (interpret (third expn) (add-var env (first (second expn)) (interpret (second (second expn)) env))))) ;; -- define if (def is-if? (fn [expn] (and (list? expn) (= 4 (count expn)) (= 'if (first expn))))) (def interpret-if (fn [expn env] (cond (interpret (second expn) env) (interpret (third expn) env) :else (interpret (fourth expn) env)))) ;; -- define function-application (def is-function-application? (fn [expn env] (and (list? expn) (= 2 (count expn)) (is-function? (interpret (first expn) env))))) (def interpret-function-application (fn [expn env] (let [function (interpret (first expn) env)] (interpret (third function) (add-var env (first (second function)) (interpret (second expn) env)))))) ;; the interpreter itself (def interpret (fn [expn env] (cond do-trace (println "Interpret is processing: " expn)) (cond ; basic values (is-number? expn) (interpret-number expn env) (is-symbol? expn) (interpret-symbol expn env) (is-boolean? expn) (interpret-boolean expn env) (is-function? expn) (interpret-function expn env) ; built-in functions (is-plus? expn) (interpret-plus expn env) (is-minus? expn) (interpret-minus expn env) (is-times? expn) (interpret-times expn env) (is-divides? expn) (interpret-divides expn env) (is-equals? expn) (interpret-equals expn env) (is-greater-than? expn) (interpret-greater-than expn env) (is-not? expn) (interpret-not expn env) (is-or? expn) (interpret-or expn env) (is-and? expn) (interpret-and expn env) ; special syntax (is-with? expn) (interpret-with expn env) (is-if? expn) (interpret-if expn env) ; functions (is-function-application? expn env) (interpret-function-application expn env) :else 'error)))

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  • using ajax to post comments in cakephp results in 404 error, but no errors locally?

    - by Paul
    Using an ajax helper created for use with Jquery I've created a form that posts comments to "/comments/add", and this works as expected on my local wamp server but not on my production server. On my production server I get a '404 error, cannot find /comments/add'. I've spent quite a bit of time searching for a resolution with no luck so far. I've focused on trying to identify a gap but nothing jumps out at me. Here are some observations: works as expected on local wamp server requestHandler is listed as component files on both local and production server are the same controllers folder has write access autoLayout and autoRender are both set to false Here is the form in my view: <div class="comments form"> <?php echo $ajax->form('/comments/add', 'tournament', array('url' => '/comments/add', 'update' => 'Comments', 'indicator' => 'commentSaved'));?> <fieldset> <legend><?php __('Add Comment');?></legend> <div id="commentSaved" style="display: none; float: right;"> <h2>Loading...</h2> </div> <?php echo $form->hidden('Comment.foreign_id', array('value' => $tournament['Tournament']['id'])); echo $form->hidden('Comment.belongs_to', array('value' => 'Tournament')); echo $form->input('Comment.name'); echo $form->input('Comment.email'); echo $form->input('Comment.web', array('value' => 'http://')); echo $form->input('Comment.content'); ?> </fieldset> <?php echo $form->end('Submit');?> </div> And here is my 'comment's controller add action: function add() { if($this->RequestHandler->isAjax()) { $this->autoLayout = false; $this->autoRender=false; $this->Comment->recursive =-1; $commentInfos = $this->Comment->findAllByIp($_SERVER['REMOTE_ADDR']); $spam = FALSE; foreach($commentInfos as $commentInfo) { if ( time() - strtotime($commentInfo['Comment']['created']) < 180) { $spam = TRUE; } } if ($spam === FALSE) { if (!empty($this->data)) { $this->data['Comment']['ip'] = $_SERVER['REMOTE_ADDR']; $this->Comment->create(); if ($this->Comment->save($this->data)) { $this->Comment->recursive =-1; $comments = $this->Comment->findAll(array('Comment.foreign_id' => $this->data['Comment']['foreign_id'], 'Comment.belongs_to' => $this->data['Comment']['belongs_to'], 'Comment.status' =>'approved')); $this->set(compact('comments')); $this->viewPath = 'elements'.DS.'posts'; $this->render('comments'); } } } else { $this->Comment->recursive =-1; $comments = $this->Comment->findAll(array('Comment.foreign_id' => $this->data['Comment']['foreign_id'], 'Comment.belongs_to' => $this->data['Comment']['belongs_to'], 'Comment.status' =>'approved')); $this->set(compact('comments')); $this->viewPath = 'elements'.DS.'posts'; $this->render('spam'); } } else { $this->Session->setFlash(__('Invalid Action. Please view a post to add a comment.', true)); $this->redirect(array('controller' => 'pages', 'action'=>'display', 'home')); } } As you can see I've made sure that 'autoLayout' and 'autoRender' are set to false, but in Firebug I still get a 404 error stating /comments/add cannot be found on the production server. I should also point out that I'm using jquery, jquery.form and jquery.editable as well as a ajax helper created to be used with jquery. Any help or even suggestions about how to trouble shoot this is really appreciated. Cheers, Paul

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  • How to handle failure to release a resource which is contained in a smart pointer?

    - by cj
    How should an error during resource deallocation be handled, when the object representing the resource is contained in a shared pointer? Smart pointers are a useful tool to manage resources safely. Examples of such resources are memory, disk files, database connections, or network connections. // open a connection to the local HTTP port boost::shared_ptr<Socket> socket = Socket::connect("localhost:80"); In a typical scenario, the class encapsulating the resource should be noncopyable and polymorphic. A good way to support this is to provide a factory method returning a shared pointer, and declare all constructors non-public. The shared pointers can now be copied from and assigned to freely. The object is automatically destroyed when no reference to it remains, and the destructor then releases the resource. /** A TCP/IP connection. */ class Socket { public: static boost::shared_ptr<Socket> connect(const std::string& address); virtual ~Socket(); protected: Socket(const std::string& address); private: // not implemented Socket(const Socket&); Socket& operator=(const Socket&); }; But there is a problem with this approach. The destructor must not throw, so a failure to release the resource will remain undetected. A common way out of this problem is to add a public method to release the resource. class Socket { public: virtual void close(); // may throw // ... }; Unfortunately, this approach introduces another problem: Our objects may now contain resources which have already been released. This complicates the implementation of the resource class. Even worse, it makes it possible for clients of the class to use it incorrectly. The following example may seem far-fetched, but it is a common pitfall in multi-threaded code. socket->close(); // ... size_t nread = socket->read(&buffer[0], buffer.size()); // wrong use! Either we ensure that the resource is not released before the object is destroyed, thereby losing any way to deal with a failed resource deallocation. Or we provide a way to release the resource explicitly during the object's lifetime, thereby making it possible to use the resource class incorrectly. There is a way out of this dilemma. But the solution involves using a modified shared pointer class. These modifications are likely to be controversial. Typical shared pointer implementations, such as boost::shared_ptr, require that no exception be thrown when their object's destructor is called. Generally, no destructor should ever throw, so this is a reasonable requirement. These implementations also allow a custom deleter function to be specified, which is called in lieu of the destructor when no reference to the object remains. The no-throw requirement is extended to this custom deleter function. The rationale for this requirement is clear: The shared pointer's destructor must not throw. If the deleter function does not throw, nor will the shared pointer's destructor. However, the same holds for other member functions of the shared pointer which lead to resource deallocation, e.g. reset(): If resource deallocation fails, no exception can be thrown. The solution proposed here is to allow custom deleter functions to throw. This means that the modified shared pointer's destructor must catch exceptions thrown by the deleter function. On the other hand, member functions other than the destructor, e.g. reset(), shall not catch exceptions of the deleter function (and their implementation becomes somewhat more complicated). Here is the original example, using a throwing deleter function: /** A TCP/IP connection. */ class Socket { public: static SharedPtr<Socket> connect(const std::string& address); protected: Socket(const std::string& address); virtual Socket() { } private: struct Deleter; // not implemented Socket(const Socket&); Socket& operator=(const Socket&); }; struct Socket::Deleter { void operator()(Socket* socket) { // Close the connection. If an error occurs, delete the socket // and throw an exception. delete socket; } }; SharedPtr<Socket> Socket::connect(const std::string& address) { return SharedPtr<Socket>(new Socket(address), Deleter()); } We can now use reset() to free the resource explicitly. If there is still a reference to the resource in another thread or another part of the program, calling reset() will only decrement the reference count. If this is the last reference to the resource, the resource is released. If resource deallocation fails, an exception is thrown. SharedPtr<Socket> socket = Socket::connect("localhost:80"); // ... socket.reset();

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  • Suggestions on how to map from Domain (ORM) objects to Data Transfer Objects (DTO)

    - by FryHard
    The current system that I am working on makes use of Castle Activerecord to provide ORM (Object Relational Mapping) between the Domain objects and the database. This is all well and good and at most times actually works well! The problem comes about with Castle Activerecords support for asynchronous execution, well, more specifically the SessionScope that manages the session that objects belong to. Long story short, bad stuff happens! We are therefore looking for a way to easily convert (think automagically) from the Domain objects (who know that a DB exists and care) to the DTO object (who know nothing about the DB and care not for sessions, mapping attributes or all thing ORM). Does anyone have suggestions on doing this. For the start I am looking for a basic One to One mapping of object. Domain object Person will be mapped to say PersonDTO. I do not want to do this manually since it is a waste. Obviously reflection comes to mind, but I am hoping with some of the better IT knowledge floating around this site that "cooler" will be suggested. Oh, I am working in C#, the ORM objects as said before a mapped with Castle ActiveRecord. Example code: By @ajmastrean's request I have linked to an example that I have (badly) mocked together. The example has a capture form, capture form controller, domain objects, activerecord repository and an async helper. It is slightly big (3MB) because I included the ActiveRecored dll's needed to get it running. You will need to create a database called ActiveRecordAsync on your local machine or just change the .config file. Basic details of example: The Capture Form The capture form has a reference to the contoller private CompanyCaptureController MyController { get; set; } On initialise of the form it calls MyController.Load() private void InitForm () { MyController = new CompanyCaptureController(this); MyController.Load(); } This will return back to a method called LoadComplete() public void LoadCompleted (Company loadCompany) { _context.Post(delegate { CurrentItem = loadCompany; bindingSource.DataSource = CurrentItem; bindingSource.ResetCurrentItem(); //TOTO: This line will thow the exception since the session scope used to fetch loadCompany is now gone. grdEmployees.DataSource = loadCompany.Employees; }, null); } } this is where the "bad stuff" occurs, since we are using the child list of Company that is set as Lazy load. The Controller The controller has a Load method that was called from the form, it then calls the Asyc helper to asynchronously call the LoadCompany method and then return to the Capture form's LoadComplete method. public void Load () { new AsyncListLoad<Company>().BeginLoad(LoadCompany, Form.LoadCompleted); } The LoadCompany() method simply makes use of the Repository to find a know company. public Company LoadCompany() { return ActiveRecordRepository<Company>.Find(Setup.company.Identifier); } The rest of the example is rather generic, it has two domain classes which inherit from a base class, a setup file to instert some data and the repository to provide the ActiveRecordMediator abilities.

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  • Do you know of a C macro to compute Unix time and date?

    - by Alexis Wilke
    I'm wondering if someone knows/has a C macro to compute a static Unix time from a hard coded date and time as in: time_t t = UNIX_TIMESTAMP(2012, 5, 10, 9, 26, 13); I'm looking into that because I want to have a numeric static timestamp. This will be done hundred of times throughout the software, each time with a different date, and I want to make sure it is fast because it will run hundreds of times every second. Converting dates that many times would definitively slow down things (i.e. calling mktime() is slower than having a static number compiled in place, right?) [made an update to try to render this paragraph clearer, Nov 23, 2012] Update I want to clarify the question with more information about the process being used. As my server receives requests, for each request, it starts a new process. That process is constantly updated with new plugins and quite often such updates require a database update. Those must be run only once. To know whether an update is necessary, I want to use a Unix date (which is better than using a counter because a counter is much more likely to break once in a while.) The plugins will thus receive an update signal and have their on_update() function called. There I want to do something like this: void some_plugin::on_update(time_t last_update) { if(last_update < UNIX_TIMESTAMP(2010, 3, 22, 20, 9, 26)) { ...run update... } if(last_update < UNIX_TIMESTAMP(2012, 5, 10, 9, 26, 13)) { ...run update... } // as many test as required... } As you can see, if I have to compute the unix timestamp each time, this could represent thousands of calls per process and if you receive 100 hits a second x 1000 calls, you wasted 100,000 calls when you could have had the compiler compute those numbers once at compile time. Putting the value in a static variable is of no interest because this code will run once per process run. Note that the last_update variable changes depending on the website being hit (it comes from the database.) Code Okay, I got the code now: // helper (Days in February) #define _SNAP_UNIX_TIMESTAMP_FDAY(year) \ (((year) % 400) == 0 ? 29LL : \ (((year) % 100) == 0 ? 28LL : \ (((year) % 4) == 0 ? 29LL : \ 28LL))) // helper (Days in the year) #define _SNAP_UNIX_TIMESTAMP_YDAY(year, month, day) \ ( \ /* January */ static_cast<qint64>(day) \ /* February */ + ((month) >= 2 ? 31LL : 0LL) \ /* March */ + ((month) >= 3 ? _SNAP_UNIX_TIMESTAMP_FDAY(year) : 0LL) \ /* April */ + ((month) >= 4 ? 31LL : 0LL) \ /* May */ + ((month) >= 5 ? 30LL : 0LL) \ /* June */ + ((month) >= 6 ? 31LL : 0LL) \ /* July */ + ((month) >= 7 ? 30LL : 0LL) \ /* August */ + ((month) >= 8 ? 31LL : 0LL) \ /* September */+ ((month) >= 9 ? 31LL : 0LL) \ /* October */ + ((month) >= 10 ? 30LL : 0LL) \ /* November */ + ((month) >= 11 ? 31LL : 0LL) \ /* December */ + ((month) >= 12 ? 30LL : 0LL) \ ) #define SNAP_UNIX_TIMESTAMP(year, month, day, hour, minute, second) \ ( /* time */ static_cast<qint64>(second) \ + static_cast<qint64>(minute) * 60LL \ + static_cast<qint64>(hour) * 3600LL \ + /* year day (month + day) */ (_SNAP_UNIX_TIMESTAMP_YDAY(year, month, day) - 1) * 86400LL \ + /* year */ (static_cast<qint64>(year) - 1970LL) * 31536000LL \ + ((static_cast<qint64>(year) - 1969LL) / 4LL) * 86400LL \ - ((static_cast<qint64>(year) - 1901LL) / 100LL) * 86400LL \ + ((static_cast<qint64>(year) - 1601LL) / 400LL) * 86400LL ) WARNING: Do not use these macros to dynamically compute a date. It is SLOWER than mktime(). This being said, if you have a hard coded date, then the compiler will compute the time_t value at compile time. Slower to compile, but faster to execute over and over again.

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  • How to Correct & Improve the Design of this Code?

    - by DaveDev
    HI Guys, I've been working on a little experiement to see if I could create a helper method to serialize any of my types to any type of HTML tag I specify. I'm getting a NullReferenceException when _writer = _viewContext.Writer; is called in protected virtual void Dispose(bool disposing) {/*...*/} I think I'm at a point where it almost works (I've gotten other implementations to work) and I was wondering if somebody could point out what I'm doing wrong? Also, I'd be interested in hearing suggestions on how I could improve the design? So basically, I have this code that will generate a Select box with a number of options: // the idea is I can use one method to create any complete tag of any type // and put whatever I want in the content area <% using (Html.GenerateTag<SelectTag>(Model, new { href = Url.Action("ActionName") })) { %> <%foreach (var fund in Model.Funds) {%> <% using (Html.GenerateTag<OptionTag>(fund)) { %> <%= fund.Name %> <% } %> <% } %> <% } %> This Html.GenerateTag helper is defined as: public static MMTag GenerateTag<T>(this HtmlHelper htmlHelper, object elementData, object attributes) where T : MMTag { return (T)Activator.CreateInstance(typeof(T), htmlHelper.ViewContext, elementData, attributes); } Depending on the type of T it'll create one of the types defined below, public class HtmlTypeBase : MMTag { public HtmlTypeBase() { } public HtmlTypeBase(ViewContext viewContext, params object[] elementData) { base._viewContext = viewContext; base.MergeDataToTag(viewContext, elementData); } } public class SelectTag : HtmlTypeBase { public SelectTag(ViewContext viewContext, params object[] elementData) { base._tag = new TagBuilder("select"); //base.MergeDataToTag(viewContext, elementData); } } public class OptionTag : HtmlTypeBase { public OptionTag(ViewContext viewContext, params object[] elementData) { base._tag = new TagBuilder("option"); //base.MergeDataToTag(viewContext, _elementData); } } public class AnchorTag : HtmlTypeBase { public AnchorTag(ViewContext viewContext, params object[] elementData) { base._tag = new TagBuilder("a"); //base.MergeDataToTag(viewContext, elementData); } } all of these types (anchor, select, option) inherit from HtmlTypeBase, which is intended to perform base.MergeDataToTag(viewContext, elementData);. This doesn't happen though. It works if I uncomment the MergeDataToTag methods in the derived classes, but I don't want to repeat that same code for every derived class I create. This is the definition for MMTag: public class MMTag : IDisposable { internal bool _disposed; internal ViewContext _viewContext; internal TextWriter _writer; internal TagBuilder _tag; internal object[] _elementData; public MMTag() {} public MMTag(ViewContext viewContext, params object[] elementData) { } public void Dispose() { Dispose(true /* disposing */); GC.SuppressFinalize(this); } protected virtual void Dispose(bool disposing) { if (!_disposed) { _disposed = true; _writer = _viewContext.Writer; _writer.Write(_tag.ToString(TagRenderMode.EndTag)); } } protected void MergeDataToTag(ViewContext viewContext, object[] elementData) { Type elementDataType = elementData[0].GetType(); foreach (PropertyInfo prop in elementDataType.GetProperties()) { if (prop.PropertyType.IsPrimitive || prop.PropertyType == typeof(Decimal) || prop.PropertyType == typeof(String)) { object propValue = prop.GetValue(elementData[0], null); string stringValue = propValue != null ? propValue.ToString() : String.Empty; _tag.Attributes.Add(prop.Name, stringValue); } } var dic = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase); var attributes = elementData[1]; if (attributes != null) { foreach (PropertyDescriptor descriptor in TypeDescriptor.GetProperties(attributes)) { object value = descriptor.GetValue(attributes); dic.Add(descriptor.Name, value); } } _tag.MergeAttributes<string, object>(dic); _viewContext = viewContext; _viewContext.Writer.Write(_tag.ToString(TagRenderMode.StartTag)); } } Thanks Dave

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  • Employee Info Starter Kit - Visual Studio 2010 and .NET 4.0 Version (4.0.0) Available

    - by joycsharp
    Employee Info Starter Kit is a ASP.NET based web application, which includes very simple user requirements, where we can create, read, update and delete (crud) the employee info of a company. Based on just a database table, it explores and solves all major problems in web development architectural space.  This open source starter kit extensively uses major features available in latest Visual Studio, ASP.NET and Sql Server to make robust, scalable, secured and maintanable web applications quickly and easily. Since it's first release, this starter kit achieved a huge popularity in web developer community and includes 1,40,000+ download from project web site. Visual Studio 2010 and .NET 4.0 came up with lots of exciting features to make software developers life easier.  A new version (v4.0.0) of Employee Info Starter Kit is now available in both MSDN Code Gallery and CodePlex. Chckout the latest version of this starter kit to enjoy cool features available in Visual Studio 2010 and .NET 4.0. [ Release Notes ] Architectural Overview Simple 2 layer architecture (user interface and data access layer) with 1 optional cache layer ASP.NET Web Form based user interface Custom Entity Data Container implemented (with primitive C# types for data fields) Active Record Design Pattern based Data Access Layer, implemented in C# and Entity Framework 4.0 Sql Server Stored Procedure to perform actual CRUD operation Standard infrastructure (architecture, helper utility) for automated integration (bottom up manner) and unit testing Technology UtilizedProgramming Languages/Scripts Browser side: JavaScript Web server side: C# 4.0 Database server side: T-SQL .NET Framework Components .NET 4.0 Entity Framework .NET 4.0 Optional/Named Parameters .NET 4.0 Tuple .NET 3.0+ Extension Method .NET 3.0+ Lambda Expressions .NET 3.0+ Aanonymous Type .NET 3.0+ Query Expressions .NET 3.0+ Automatically Implemented Properties .NET 3.0+ LINQ .NET 2.0 + Partial Classes .NET 2.0 + Generic Type .NET 2.0 + Nullable Type   ASP.NET 3.5+ List View (TBD) ASP.NET 3.5+ Data Pager (TBD) ASP.NET 2.0+ Grid View ASP.NET 2.0+ Form View ASP.NET 2.0+ Skin ASP.NET 2.0+ Theme ASP.NET 2.0+ Master Page ASP.NET 2.0+ Object Data Source ASP.NET 1.0+ Role Based Security Visual Studio Features Visual Studio 2010 CodedUI Test Visual Studio 2010 Layer Diagram Visual Studio 2010 Sequence Diagram Visual Studio 2010 Directed Graph Visual Studio 2005+ Database Unit Test Visual Studio 2005+ Unit Test Visual Studio 2005+ Web Test Visual Studio 2005+ Load Test Sql Server Features Sql Server 2005 Stored Procedure Sql Server 2005 Xml type Sql Server 2005 Paging support

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  • Employee Info Starter Kit - Visual Studio 2010 and .NET 4.0 Version (4.0.0) Available

    - by Mohammad Ashraful Alam
    Employee Info Starter Kit is a ASP.NET based web application, which includes very simple user requirements, where we can create, read, update and delete (crud) the employee info of a company. Based on just a database table, it explores and solves most of the major problems in web development architectural space.  This open source starter kit extensively uses major features available in latest Visual Studio, ASP.NET and Sql Server to make robust, scalable, secured and maintanable web applications quickly and easily. Since it's first release, this starter kit achieved a huge popularity in web developer community and includes 1,40,000+ download from project web site. Visual Studio 2010 and .NET 4.0 came up with lots of exciting features to make software developers life easier.  A new version (v4.0.0) of Employee Info Starter Kit is now available in both MSDN Code Gallery and CodePlex. Chckout the latest version of this starter kit to enjoy cool features available in Visual Studio 2010 and .NET 4.0. [ Release Notes ] Architectural Overview Simple 2 layer architecture (user interface and data access layer) with 1 optional cache layer ASP.NET Web Form based user interface Custom Entity Data Container implemented (with primitive C# types for data fields) Active Record Design Pattern based Data Access Layer, implemented in C# and Entity Framework 4.0 Sql Server Stored Procedure to perform actual CRUD operation Standard infrastructure (architecture, helper utility) for automated integration (bottom up manner) and unit testing Technology UtilizedProgramming Languages/Scripts Browser side: JavaScript Web server side: C# 4.0 Database server side: T-SQL .NET Framework Components .NET 4.0 Entity Framework .NET 4.0 Optional/Named Parameters .NET 4.0 Tuple .NET 3.0+ Extension Method .NET 3.0+ Lambda Expressions .NET 3.0+ Aanonymous Type .NET 3.0+ Query Expressions .NET 3.0+ Automatically Implemented Properties .NET 3.0+ LINQ .NET 2.0 + Partial Classes .NET 2.0 + Generic Type .NET 2.0 + Nullable Type   ASP.NET 3.5+ List View (TBD) ASP.NET 3.5+ Data Pager (TBD) ASP.NET 2.0+ Grid View ASP.NET 2.0+ Form View ASP.NET 2.0+ Skin ASP.NET 2.0+ Theme ASP.NET 2.0+ Master Page ASP.NET 2.0+ Object Data Source ASP.NET 1.0+ Role Based Security Visual Studio Features Visual Studio 2010 CodedUI Test Visual Studio 2010 Layer Diagram Visual Studio 2010 Sequence Diagram Visual Studio 2010 Directed Graph Visual Studio 2005+ Database Unit Test Visual Studio 2005+ Unit Test Visual Studio 2005+ Web Test Visual Studio 2005+ Load Test Sql Server Features Sql Server 2005 Stored Procedure Sql Server 2005 Xml type Sql Server 2005 Paging support

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  • Creating a dynamic proxy generator with c# – Part 4 – Calling the base method

    - by SeanMcAlinden
    Creating a dynamic proxy generator with c# – Part 1 – Creating the Assembly builder, Module builder and caching mechanism Creating a dynamic proxy generator with c# – Part 2 – Interceptor Design Creating a dynamic proxy generator with c# – Part 3 – Creating the constructors   The plan for calling the base methods from the proxy is to create a private method for each overridden proxy method, this will allow the proxy to use a delegate to simply invoke the private method when required. Quite a few helper classes have been created to make this possible so as usual I would suggest download or viewing the code at http://rapidioc.codeplex.com/. In this post I’m just going to cover the main points for when creating methods. Getting the methods to override The first two notable methods are for getting the methods. private static MethodInfo[] GetMethodsToOverride<TBase>() where TBase : class {     return typeof(TBase).GetMethods().Where(x =>         !methodsToIgnore.Contains(x.Name) &&                              (x.Attributes & MethodAttributes.Final) == 0)         .ToArray(); } private static StringCollection GetMethodsToIgnore() {     return new StringCollection()     {         "ToString",         "GetHashCode",         "Equals",         "GetType"     }; } The GetMethodsToIgnore method string collection contains an array of methods that I don’t want to override. In the GetMethodsToOverride method, you’ll notice a binary AND which is basically saying not to include any methods marked final i.e. not virtual. Creating the MethodInfo for calling the base method This method should hopefully be fairly easy to follow, it’s only function is to create a MethodInfo which points to the correct base method, and with the correct parameters. private static MethodInfo CreateCallBaseMethodInfo<TBase>(MethodInfo method) where TBase : class {     Type[] baseMethodParameterTypes = ParameterHelper.GetParameterTypes(method, method.GetParameters());       return typeof(TBase).GetMethod(        method.Name,        BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic,        null,        baseMethodParameterTypes,        null     ); }   /// <summary> /// Get the parameter types. /// </summary> /// <param name="method">The method.</param> /// <param name="parameters">The parameters.</param> public static Type[] GetParameterTypes(MethodInfo method, ParameterInfo[] parameters) {     Type[] parameterTypesList = Type.EmptyTypes;       if (parameters.Length > 0)     {         parameterTypesList = CreateParametersList(parameters);     }     return parameterTypesList; }   Creating the new private methods for calling the base method The following method outline how I’ve created the private methods for calling the base class method. private static MethodBuilder CreateCallBaseMethodBuilder(TypeBuilder typeBuilder, MethodInfo method) {     string callBaseSuffix = "GetBaseMethod";       if (method.IsGenericMethod || method.IsGenericMethodDefinition)     {                         return MethodHelper.SetUpGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     }     else     {         return MethodHelper.SetupNonGenericMethod             (                 typeBuilder,                 method,                 method.Name + callBaseSuffix,                 MethodAttributes.Private | MethodAttributes.HideBySig             );     } } The CreateCallBaseMethodBuilder is the entry point method for creating the call base method. I’ve added a suffix to the base classes method name to keep it unique. Non Generic Methods Creating a non generic method is fairly simple public static MethodBuilder SetupNonGenericMethod(     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       Type returnType = method.ReturnType;       MethodBuilder methodBuilder = CreateMethodBuilder         (             typeBuilder,             method,             methodName,             methodAttributes,             parameterTypes,             returnType         );       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static MethodBuilder CreateMethodBuilder (     TypeBuilder typeBuilder,     MethodInfo method,     string methodName,     MethodAttributes methodAttributes,     Type[] parameterTypes,     Type returnType ) { MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName, methodAttributes, returnType, parameterTypes); return methodBuilder; } As you can see, you simply have to declare a method builder, get the parameter types, and set the method attributes you want.   Generic Methods Creating generic methods takes a little bit more work. /// <summary> /// Sets up generic method. /// </summary> /// <param name="typeBuilder">The type builder.</param> /// <param name="method">The method.</param> /// <param name="methodName">Name of the method.</param> /// <param name="methodAttributes">The method attributes.</param> public static MethodBuilder SetUpGenericMethod     (         TypeBuilder typeBuilder,         MethodInfo method,         string methodName,         MethodAttributes methodAttributes     ) {     ParameterInfo[] parameters = method.GetParameters();       Type[] parameterTypes = ParameterHelper.GetParameterTypes(method, parameters);       MethodBuilder methodBuilder = typeBuilder.DefineMethod(methodName,         methodAttributes);       Type[] genericArguments = method.GetGenericArguments();       GenericTypeParameterBuilder[] genericTypeParameters =         GetGenericTypeParameters(methodBuilder, genericArguments);       ParameterHelper.SetUpParameterConstraints(parameterTypes, genericTypeParameters);       SetUpReturnType(method, methodBuilder, genericTypeParameters);       if (method.IsGenericMethod)     {         methodBuilder.MakeGenericMethod(genericArguments);     }       ParameterHelper.SetUpParameters(parameterTypes, parameters, methodBuilder);       return methodBuilder; }   private static GenericTypeParameterBuilder[] GetGenericTypeParameters     (         MethodBuilder methodBuilder,         Type[] genericArguments     ) {     return methodBuilder.DefineGenericParameters(GenericsHelper.GetArgumentNames(genericArguments)); }   private static void SetUpReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.IsGenericMethodDefinition)     {         SetUpGenericDefinitionReturnType(method, methodBuilder, genericTypeParameters);     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     } }   private static void SetUpGenericDefinitionReturnType(MethodInfo method, MethodBuilder methodBuilder, GenericTypeParameterBuilder[] genericTypeParameters) {     if (method.ReturnType == null)     {         methodBuilder.SetReturnType(typeof(void));     }     else if (method.ReturnType.IsGenericType)     {         methodBuilder.SetReturnType(genericTypeParameters.Where             (x => x.Name == method.ReturnType.Name).First());     }     else     {         methodBuilder.SetReturnType(method.ReturnType);     }             } Ok, there are a few helper methods missing, basically there is way to much code to put in this post, take a look at the code at http://rapidioc.codeplex.com/ to follow it through completely. Basically though, when dealing with generics there is extra work to do in terms of getting the generic argument types setting up any generic parameter constraints setting up the return type setting up the method as a generic All of the information is easy to get via reflection from the MethodInfo.   Emitting the new private method Emitting the new private method is relatively simple as it’s only function is calling the base method and returning a result if the return type is not void. ILGenerator il = privateMethodBuilder.GetILGenerator();   EmitCallBaseMethod(method, callBaseMethod, il);   private static void EmitCallBaseMethod(MethodInfo method, MethodInfo callBaseMethod, ILGenerator il) {     int privateParameterCount = method.GetParameters().Length;       il.Emit(OpCodes.Ldarg_0);       if (privateParameterCount > 0)     {         for (int arg = 0; arg < privateParameterCount; arg++)         {             il.Emit(OpCodes.Ldarg_S, arg + 1);         }     }       il.Emit(OpCodes.Call, callBaseMethod);       il.Emit(OpCodes.Ret); } So in the main method building method, an ILGenerator is created from the method builder. The ILGenerator performs the following actions: Load the class (this) onto the stack using the hidden argument Ldarg_0. Create an argument on the stack for each of the method parameters (starting at 1 because 0 is the hidden argument) Call the base method using the Opcodes.Call code and the MethodInfo we created earlier. Call return on the method   Conclusion Now we have the private methods prepared for calling the base method, we have reached the last of the relatively easy part of the proxy building. Hopefully, it hasn’t been too hard to follow so far, there is a lot of code so I haven’t been able to post it all so please check it out at http://rapidioc.codeplex.com/. The next section should be up fairly soon, it’s going to cover creating the delegates for calling the private methods created in this post.   Kind Regards, Sean.

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  • The HTG Guide to Using a Bluetooth Keyboard with Your Android Device

    - by Matt Klein
    Android devices aren’t usually associated with physical keyboards. But, since Google is now bundling their QuickOffice app with the newly-released Kit-Kat, it appears inevitable that at least some Android tablets (particularly 10-inch models) will take on more productivity roles. In recent years, physical keyboards have been rendered obsolete by swipe style input methods such as Swype and Google Keyboard. Physical keyboards tend to make phones thick and plump, and that won’t fly today when thin (and even flexible and curved) is in vogue. So, you’ll be hard-pressed to find smartphone manufacturers launching new models with physical keyboards, thus rendering sliders to a past chapter in mobile phone evolution. It makes sense to ditch the clunky keyboard phone in favor of a lighter, thinner model. You’re going to carry around in your pocket or purse all day, why have that extra bulk and weight? That said, there is sound logic behind pairing tablets with keyboards. Microsoft continues to plod forward with its Surface models, and while critics continue to lavish praise on the iPad, its functionality is obviously enhanced and extended when you add a physical keyboard. Apple even has an entire page devoted specifically to iPad-compatible keyboards. But an Android tablet and a keyboard? Does such a thing even exist? They do actually. There are docking keyboards and keyboard/case combinations, there’s the Asus Transformer family, Logitech markets a Windows 8 keyboard that speaks “Android”, and these are just to name a few. So we know that keyboard products that are designed to work with Android exist, but what about an everyday Bluetooth keyboard you might use with Windows or OS X? How-To Geek wanted look at how viable it is to use such a keyboard with Android. We conducted some research and examined some lists of Android keyboard shortcuts. Most of what we found was long outdated. Many of the shortcuts don’t even apply anymore, while others just didn’t work. Regardless, after a little experimentation and a dash of customization, it turns out using a keyboard with Android is kind of fun, and who knows, maybe it will catch on. Setting things up Setting up a Bluetooth keyboard with Android is very easy. First, you’ll need a Bluetooth keyboard and of course an Android device, preferably running version 4.1 (Jelly Bean) or higher. For our test, we paired a second-generation Google Nexus 7 running Android 4.3 with a Samsung Series 7 keyboard. In Android, enable Bluetooth if it isn’t already on. We’d like to note that if you don’t normally use Bluetooth accessories and peripherals with your Android device (or any device really), it’s best practice to leave Bluetooth off because, like GPS, it drains the device’s battery more quickly. To enable Bluetooth, simply go to “Settings” -> “Bluetooth” and tap the slider button to “On”. To set up the keyboard, make sure it is on and then tap “Bluetooth” in the Android settings. On the resulting screen, your Android device should automatically search for and hopefully find your keyboard. If you don’t get it right the first time, simply turn the keyboard on again and then tap “Search for Devices” to try again. If it still doesn’t work, make sure you have fresh batteries and the keyboard isn’t paired to another device. If it is, you will need to unpair it before it will work with your Android device (consult your keyboard manufacturer’s documentation or Google if you don’t know how to do this). When Android finds your keyboard, select it under “Available Devices” … … and you should be prompted to type in a code: If successful, you will see that device is now “Connected” and you’re ready to go. If you want to test things out, try pressing the “Windows” key (“Apple” or “Command”) + ESC, and you will be whisked to your Home screen. So, what can you do? Traditional Mac and Windows users know there’s usually a keyboard shortcut for just about everything (and if there isn’t, there’s all kinds of ways to remap keys to do a variety of commands, tasks, and functions). So where does Android fall in terms of baked-in keyboard commands? There answer to that is kind of enough, but not too much. There are definitely established combos you can use to get around, but they aren’t clear and there doesn’t appear to be any one authority on what they are. Still, there is enough keyboard functionality in Android to make it a viable option, if only for those times when you need to get something done (long e-mail or important document) and an on-screen keyboard simply won’t do. It’s important to remember that Android is, and likely always will be a touch-first interface. That said, it does make some concessions to physical keyboards. In other words, you can get around Android fairly well without having to lift your hands off the keys, but you will still have to tap the screen regularly, unless you add a mouse. For example, you can wake your device by tapping a key rather than pressing its power button. However, if your device is slide or pattern-locked, then you’ll have to use the touchscreen to unlock it – a password or PIN however, works seamlessly with a keyboard – other things like widgets and app controls and features, have to be tapped. You get the idea. Keyboard shortcuts and navigation As we said, baked-in keyboard shortcut combos aren’t necessarily abundant nor apparent. The one thing you can always do is search. Any time you want to Google something, start typing from the Home screen and the search screen will automatically open and begin displaying results. Other than that, here is what we were able to figure out: ESC = go back CTRL + ESC = menu CTRL + ALT + DEL = restart (no questions asked) ALT + SPACE = search page (say “OK Google” to voice search) ALT + TAB (ALT + SHIFT + TAB) = switch tasks Also, if you have designated volume function keys, those will probably work too. There’s also some dedicated app shortcuts like calculator, Gmail, and a few others: CMD + A = calculator CMD + C = contacts CMD + E = e-mail CMD + G = Gmail CMD + L = Calendar CMD + P = Play Music CMD + Y = YouTube Overall, it’s not a long comprehensive list and there’s no dedicated keyboard combos for the full array of Google’s products. Granted, it’s hard to imagine getting a lot of mileage out of a keyboard with Maps but with something like Keep, you could type out long, detailed lists on your tablet, and then view them on your smartphone when you go out shopping. You can also use the arrow keys to navigate your Home screen over shortcuts and open the app drawer. When something on the screen is selected, it will be highlighted in blue. Press “Enter” to open your selection. Additionally, if an app has its own set of shortcuts, e.g. Gmail has quite a few unique shortcuts to it, as does Chrome, some – though not many – will work in Android (not for YouTube though). Also, many “universal” shortcuts such as Copy (CTRL + C), Cut (CTRL + X), Paste (CTRL + V), and Select All (CTRL + A) work where needed – such as in instant messaging, e-mail, social media apps, etc. Creating custom application shortcuts What about custom shortcuts? When we were researching this article, we were under the impression that it was possible to assign keyboard combinations to specific apps, such as you could do on older Android versions such as Gingerbread. This no long seems to be the case and nowhere in “Settings” could we find a way to assign hotkey combos to any of our favorite, oft-used apps or functions. If you do want custom keyboard shortcuts, what can you do? Luckily, there’s an app on Google Play that allows you to, among other things, create custom app shortcuts. It is called External Keyboard Helper (EKH) and while there is a free demo version, the pay version is only a few bucks. We decided to give EKH a whirl and through a little experimentation and finally reading the developer’s how-to, we found we could map custom keyboard combos to just about anything. To do this, first open the application and you’ll see the main app screen. Don’t worry about choosing a custom layout or anything like that, you want to go straight to the “Advanced settings”: In the “Advanced settings” select “Application shortcuts” to continue: You can have up to 16 custom application shortcuts. We are going to create a custom shortcut to the Facebook app. We choose “A0”, and from the resulting list, Facebook. You can do this for any number of apps, services, and settings. As you can now see, the Facebook app has now been linked to application-zero (A0): Go back to the “Advanced settings” and choose “Customize keyboard mappings”: You will be prompted to create a custom keyboard layout so we choose “Custom 1”: When you choose to create a custom layout, you can do a great many more things with your keyboard. For example, many keyboards have predefined function (Fn) keys, which you can map to your tablet’s brightness controls, toggle WiFi on/off, and much more. A word of advice, the application automatically remaps certain keys when you create a custom layout. This might mess up some existing keyboard combos. If you simply want to add some functionality to your keyboard, you can go ahead and delete EKH’s default changes and start your custom layout from scratch. To create a new combo, select “Add new key mapping”: For our new shortcut, we are going to assign the Facebook app to open when we key in “ALT + F”. To do this, we press the “F” key while in the “Scancode” field and we see it returns a value of “33”. If we wanted to use a different key, we can press “Change” and scan another key’s numerical value. We now want to assign the “ALT” key to application “A0”, previously designated as the Facebook app. In the “AltGr” field, we enter “A0” and then “Save” our custom combo. And now we see our new application shortcut. Now, as long as we’re using our custom layout, every time we press “ALT + F”, the Facebook app will launch: External Keyboard Helper extends far beyond simple application shortcuts and if you are looking for deeper keyboard customization options, you should definitely check it out. Among other things, EKH also supports dozens of languages, allows you to quickly switch between layouts using a key or combo, add up to 16 custom text shortcuts, and much more! It can be had on Google Play for $2.53 for the full version, but you can try the demo version for free. More extensive documentation on how to use the app is also available. Android? Keyboard? Sure, why not? Unlike traditional desktop operating systems, you don’t need a physical keyboard and mouse to use a mobile operating system. You can buy an iPad or Nexus 10 or Galaxy Note, and never need another accessory or peripheral – they work as intended right out of the box. It’s even possible you can write the next great American novel on one these devices, though that might require a lot of practice and patience. That said, using a keyboard with Android is kind of fun. It’s not revelatory but it does elevate the experience. You don’t even need to add customizations (though they are nice) because there are enough existing keyboard shortcuts in Android to make it usable. Plus, when it comes to inputting text such as in an editor or terminal application, we fully advocate big, physical keyboards. Bottom line, if you’re looking for a way to enhance your Android tablet, give a keyboard a chance. Do you use your Android device for productivity? Is a physical keyboard an important part of your setup? Do you have any shortcuts that we missed? Sound off in the comments and let us know what you think.     

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  • Resolve a URL from a Partial View (ASP.NET MVC)

    Working on an ASP.NET MVC application and needed the ability to resolve a URL from a partial view. For example, I have an image I want to display, but I need to resolve the virtual path (say, ~/Content/Images/New.png) into a relative path that the browser can use, such as ../../Content/Images/New.png or /MyAppName/Content/Images/New.png. Astandard view derives from the System.Web.UI.Page class, meaning you have access to the ResolveUrl and ResolveClientUrl methods. Consequently, you can write markup/code like the following:' /The problem is that the above code does not work as expected in a partial view. What's a little confusing is that while the above code compiles and the page, when visited through a browser, renders, the call to Page.ResolveClientUrl returns precisely what you pass in, ~/Content/Images/New.png, in this instance. The browser doesn't know what to do with ~, it presumes it's part of the URL, so it sends the request to the server for the image with the ~ in the URL, which results in a broken image.I did a bit of searching online and found this handy tip from Stephen Walther - Using ResolveUrl in an HTML Helper. In a nutshell, Stephen shows how to create an extension method for the HtmlHelper class that uses the UrlHelper class to resolve a URL. Specifically, Stephen shows how to add an Image extension method to HtmlHelper. I incorporated Stephen's code into my codebase and also created a more generic extension method, which I named ResolveUrl.public static MvcHtmlString ResolveUrl(this HtmlHelper htmlHelper, string url) { var urlHelper = new UrlHelper(htmlHelper.ViewContext.RequestContext); return MvcHtmlString.Create(urlHelper.Content(url)); }With this method in place you can resolve a URL in a partial view like so:' /Or you could use Stephen's Html.Image extension method (althoughmy more generic Html.ResolveUrl method could be used in non-image related scenarios where you needed to get a relative URL from a virtual one in a partial view). Thanks for the helpful tip, Stephen!Happy Programming!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • Resolve a URL from a Partial View (ASP.NET MVC)

    Working on an ASP.NET MVC application and needed the ability to resolve a URL from a partial view. For example, I have an image I want to display, but I need to resolve the virtual path (say, ~/Content/Images/New.png) into a relative path that the browser can use, such as ../../Content/Images/New.png or /MyAppName/Content/Images/New.png. Astandard view derives from the System.Web.UI.Page class, meaning you have access to the ResolveUrl and ResolveClientUrl methods. Consequently, you can write markup/code like the following:' /The problem is that the above code does not work as expected in a partial view. What's a little confusing is that while the above code compiles and the page, when visited through a browser, renders, the call to Page.ResolveClientUrl returns precisely what you pass in, ~/Content/Images/New.png, in this instance. The browser doesn't know what to do with ~, it presumes it's part of the URL, so it sends the request to the server for the image with the ~ in the URL, which results in a broken image.I did a bit of searching online and found this handy tip from Stephen Walther - Using ResolveUrl in an HTML Helper. In a nutshell, Stephen shows how to create an extension method for the HtmlHelper class that uses the UrlHelper class to resolve a URL. Specifically, Stephen shows how to add an Image extension method to HtmlHelper. I incorporated Stephen's code into my codebase and also created a more generic extension method, which I named ResolveUrl.public static MvcHtmlString ResolveUrl(this HtmlHelper htmlHelper, string url) { var urlHelper = new UrlHelper(htmlHelper.ViewContext.RequestContext); return MvcHtmlString.Create(urlHelper.Content(url)); }With this method in place you can resolve a URL in a partial view like so:' /Or you could use Stephen's Html.Image extension method (althoughmy more generic Html.ResolveUrl method could be used in non-image related scenarios where you needed to get a relative URL from a virtual one in a partial view). Thanks for the helpful tip, Stephen!Happy Programming!Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • DevDays ‘00 The Netherlands day #1

    - by erwin21
    First day of DevDays 2010, I was looking forward to DevDays to see all the new things like VS2010, .NET4.0, MVC2. The lineup for this year is again better than the year before, there are 100+ session of all kind of topics like Cloud, Database, Mobile, SharePoint, User experience, Visual Studio, Web. The first session of the day was a keynote by Anders Hejlsberg he talked about the history and future of programming languages. He gave his view about trends and influences in programming languages today and in the future. The second talk that i followed was from the famous Scott Hanselman, he talked about the basics of ASP.NET MVC 2, although it was a 300 level session, it was more like a level 100 session, but it was mentioned by Scott at the beginning. Although it was interesting to see all the basic things about MVC like the controllers, actions, routes, views, models etc. After the lunch the third talk for me was about moving ASP.NET webform applications to MVC from Fritz Onion. In this session he changed an example webform application part by part to a MVC application. He gave some interesting tips and tricks and showed how to solve some issues that occur while converting. Next and the fourth talk was about the difference between LINQ to SQL and  the ADO.NET  Entity Framework from Kurt Claeys. He gave a good understanding about this two options, the demos where in LINQ to SQL and the Entity Framework, the goal was to get a good understanding when and where to use both options. The last talk about this day was also from Scott Hanselman, he goes deeper into the features of ASP.NET MVC 2 and gave some interesting tips, the ninja black belt tips. He gave some tips about the tooling, the new MVC 2 html helper methods, other view engines (like NHaml, spark),T4 templating. With this tips we can be more productive and create web applications better and faster. It was a long and interesting day, I am looking forward to day #2.

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  • sudo: /usr/lib/sudo/sudoers.so must be owned by uid 0

    - by 7UR7L3
    Whenever I try to do anything at all that requires my password it returns this: u7ur7l3@ubuntu:~$ sudo sudo: /usr/lib/sudo/sudoers.so must be owned by uid 0 sudo: fatal error, unable to load plugins u7ur7l3@ubuntu:~$ So I can't install anything from the Software Center / package manager or run any commands in terminal that require my password. I can log in, but that's pretty much it. I accidentally changed the permissions of some files, then changed some more trying to fix it :/. Now I'm completely lost as to what to do. This is what happened when I tried to get sudo working again using pkexec: u7ur7l3@ubuntu:~$ pkexec chown root /usr/lib/sudo/sudoers.so Error getting authority: Error initializing authority: Error calling StartServiceByName for org.freedesktop.PolicyKit1: GDBus.Error:org.freedesktop.DBus.Error.Spawn.ExecFailed: Failed to execute program /usr/lib/dbus-1.0/dbus-daemon-launch-helper: Success u7ur7l3@ubuntu:~$ sudo ls sudo: /usr/lib/sudo/sudoers.so must be owned by uid 0 sudo: fatal error, unable to load plugins And to change permissions I was using Root Actions as a dolphin service/ plugin thing, so history doesn't show me the permission changes. I just realized that sounds don't work at all anymore. When I go into Phonon my default settings and playback devices aren't even there. Also I don't have the option to shutdown, I can only log out or leave.

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