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  • Converting C source to C++

    - by Barry Kelly
    How would you go about converting a reasonably large (300K), fairly mature C codebase to C++? The kind of C I have in mind is split into files roughly corresponding to modules (i.e. less granular than a typical OO class-based decomposition), using internal linkage in lieu private functions and data, and external linkage for public functions and data. Global variables are used extensively for communication between the modules. There is a very extensive integration test suite available, but no unit (i.e. module) level tests. I have in mind a general strategy: Compile everything in C++'s C subset and get that working. Convert modules into huge classes, so that all the cross-references are scoped by a class name, but leaving all functions and data as static members, and get that working. Convert huge classes into instances with appropriate constructors and initialized cross-references; replace static member accesses with indirect accesses as appropriate; and get that working. Now, approach the project as an ill-factored OO application, and write unit tests where dependencies are tractable, and decompose into separate classes where they are not; the goal here would be to move from one working program to another at each transformation. Obviously, this would be quite a bit of work. Are there any case studies / war stories out there on this kind of translation? Alternative strategies? Other useful advice? Note 1: the program is a compiler, and probably millions of other programs rely on its behaviour not changing, so wholesale rewriting is pretty much not an option. Note 2: the source is nearly 20 years old, and has perhaps 30% code churn (lines modified + added / previous total lines) per year. It is heavily maintained and extended, in other words. Thus, one of the goals would be to increase mantainability. [For the sake of the question, assume that translation into C++ is mandatory, and that leaving it in C is not an option. The point of adding this condition is to weed out the "leave it in C" answers.]

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  • Why the vertical scroll bar moves automatically ?

    - by Misha Moroshko
    I don't understand why the vertical scroll bar moves automatically to the most top position when "Line 9" clicked, for example. Further clicks does not move the scroll bar. Could anyone explain why, and how to fix this ? I work with Firefox 3.6.3. <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd"> <body> <div> <table> <tr row='0'><td class='column1'>Line 0</td></tr> <tr row='1'><td class='column1'>Line 1</td></tr> <tr row='2'><td class='column1'>Line 2</td></tr> <tr row='3'><td class='column1'>Line 3</td></tr> <tr row='4'><td class='column1'>Line 4</td></tr> <tr row='5'><td class='column1'>Line 5</td></tr> <tr row='6'><td class='column1'>Line 6</td></tr> <tr row='7'><td class='column1'>Line 7</td></tr> <tr row='8'><td class='column1'>Line 8</td></tr> <tr row='9'><td class='column1'>Line 9</td></tr> </table> </div> </body> $(document).ready(function() { $(".column1").each(function(index) { $(this).after("<td class='column2'>Details " + index + "</td>"); $(this).toggle(function() { $("[row='" + index + "'] .column2").fadeIn("fast") }, function() { $("[row='" + index + "'] .column2").fadeOut("fast") }); }); }); div { overflow: auto; height: 100px; width: 300px; border: 1px solid blue; } .column1 { cursor: pointer; } .column2 { display: none; }

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  • Autoconf -- building with static library (newbie)

    - by EB
    I am trying to migrate my application from manual build to autoconf, which is working very nicely so far. But I have one static library that I can't figure out how to integrate. That library will NOT be located in the usual library locations - the location of the binary (.a file) and header (.h file) will be given as a configure argument. (Notably, even if I move the .a file to /usr/lib or anywhere else I can think of, it still won't work.) It is also not named traditionally (it does not start with "lib" or "l"). Manual compilation is working with these (directory is not predictable - this is just an example): gcc ... -I/home/john/mystuff /home/john/mystuff/helper.a (Uh, I actually don't understand why the .a file is referenced directly, not with -L or anything. Yes, I have a half-baked understanding of building C programs.) So, in my configure.ac, I can use the relevant configure argument to successfully find the header (.h file) using AC_CHECK_HEADER. Inside the AC_CHECK_HEADER I then add the location to CPFLAGS and the #include of the header file in the actual C code picks it up nicely. Given a configure argument that has been put into $location and the name of the needed files are helper.h and helper.a (which are both in the same directory), here is what works so far: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"]) Where I run into difficulties is getting the binary (.a file) linked in. No matter what I try, I always get an error about undefined references to the function calls for that library. I'm pretty sure it's a linkage issue, because I can fuss with the C code and make an intentional error in the function calls to that library which produces earlier errors that indicate that the function prototypes have been loaded and used to compile. I tried adding the location that contains the .a file to LDFLAGS and then doing a AC_CHECK_LIB but it is not found. Maybe my syntax is wrong, or maybe I'm missing something more fundamental, which would not be surprising since I'm a newbie and don't really know what I'm doing. Here is what I have tried: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS -L$location"; AC_CHECK_LIB(helper)]) No dice. AC_CHECK_LIB is looking for -lhelper I guess (or libhelper?) so I'm not sure if that's a problem, so I tried this, too (omit AC_CHECK_LIB and include the .a directly in LDFLAGS), without luck: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS -L$location/helper.a"]) To emulate the manual compilation, I tried removing the -L but that doesn't help: AC_CHECK_HEADER([$location/helper.h], [AC_DEFINE([HAVE_HELPER_H], [1], [found helper.h]) CFLAGS="$CFLAGS -I$location"; LDFLAGS="$LDFLAGS $location/helper.a"]) I tried other combinations and permutations, but I think I might be missing something more fundamental....

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  • Emacs, C++ code completion for vectors

    - by Caglar Toklu
    Hi, I am new to Emacs, and I have the following code as a sample. I have installed GNU Emacs 23.1.1 (i386-mingw-nt6.1.7600), installed cedet-1.0pre7.tar.gz. , installed ELPA, and company. You can find my simple Emacs configuration at the bottom. The problem is, when I type q[0] in main() and press . (dot), I see the 37 members of the vector, not Person although first_name and last_name are expected. The completion works as expected in the function greet() but it has nothing to do with vector. My question is, how can I accomplish code completion for vector elements too? #include <iostream> #include <vector> using namespace std; class Person { public: string first_name; string last_name; }; void greet(Person a_person) { // a_person.first_name is completed as expected! cout << a_person.first_name << "|"; cout << a_person.last_name << endl; }; int main() { vector<Person> q(2); Person guy1; guy1.first_name = "foo"; guy1.last_name = "bar"; Person guy2; guy2.first_name = "stack"; guy2.last_name = "overflow"; q[0] = guy1; q[1] = guy2; greet(guy1); greet(guy2); // cout q[0]. I want to see first_name or last_name here! } My Emacs configuration: ;;; This was installed by package-install.el. ;;; This provides support for the package system and ;;; interfacing with ELPA, the package archive. ;;; Move this code earlier if you want to reference ;;; packages in your .emacs. (when (load (expand-file-name "~/.emacs.d/elpa/package.el")) (package-initialize)) (load-file "~/.emacs.d/cedet/common/cedet.el") (semantic-load-enable-excessive-code-helpers) (require 'semantic-ia) (global-srecode-minor-mode 1) (semantic-add-system-include "/gcc/include/c++/4.4.2" 'c++-mode) (semantic-add-system-include "/gcc/i386-pc-mingw32/include" 'c++-mode) (semantic-add-system-include "/gcc/include" 'c++-mode) (defun my-semantic-hook () (imenu-add-to-menubar "TAGS")) (add-hook 'semantic-init-hooks 'my-semantic-hook)

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  • WinForm-style Invoke() in unmanaged C++

    - by Matt Green
    I've been playing with a DataBus-type design for a hobby project, and I ran into an issue. Back-end components need to notify the UI that something has happened. My implementation of the bus delivers the messages synchronously with respect to the sender. In other words, when you call Send(), the method blocks until all the handlers have called. (This allows callers to use stack memory management for event objects.) However, consider the case where an event handler updates the GUI in response to an event. If the handler is called, and the message sender lives on another thread, then the handler cannot update the GUI due to Win32's GUI elements having thread affinity. More dynamic platforms such as .NET allow you to handle this by calling a special Invoke() method to move the method call (and the arguments) to the UI thread. I'm guessing they use the .NET parking window or the like for these sorts of things. A morbid curiosity was born: can we do this in C++, even if we limit the scope of the problem? Can we make it nicer than existing solutions? I know Qt does something similar with the moveToThread() function. By nicer, I'll mention that I'm specifically trying to avoid code of the following form: if(! this->IsUIThread()) { Invoke(MainWindowPresenter::OnTracksAdded, e); return; } being at the top of every UI method. This dance was common in WinForms when dealing with this issue. I think this sort of concern should be isolated from the domain-specific code and a wrapper object made to deal with it. My implementation consists of: DeferredFunction - functor that stores the target method in a FastDelegate, and deep copies the single event argument. This is the object that is sent across thread boundaries. UIEventHandler - responsible for dispatching a single event from the bus. When the Execute() method is called, it checks the thread ID. If it does not match the UI thread ID (set at construction time), a DeferredFunction is allocated on the heap with the instance, method, and event argument. A pointer to it is sent to the UI thread via PostThreadMessage(). Finally, a hook function for the thread's message pump is used to call the DeferredFunction and de-allocate it. Alternatively, I can use a message loop filter, since my UI framework (WTL) supports them. Ultimately, is this a good idea? The whole message hooking thing makes me leery. The intent is certainly noble, but are there are any pitfalls I should know about? Or is there an easier way to do this?

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  • jQuery AJAX POST gives undefined index

    - by Sebastian
    My eventinfo.php is giving the following output: <br /> <b>Notice</b>: Undefined index: club in <b>/homepages/19/d361310357/htdocs/guestvibe/wp-content/themes/yasmin/guestvibe/eventinfo.php</b> on line <b>11</b><br /> [] HTML (index.php): <select name="club" class="dropdown" id="club"> <?php getClubs(); ?> </select> jQuery (index.php): <script type="text/javascript"> $(document).ready(function() { $.ajax({ type: "POST", url: "http://www.guestvibe.com/wp-content/themes/yasmin/guestvibe/eventinfo.php", data: $('#club').serialize(), success: function(data) { $('#rightbox_inside').html('<h2>' + $('#club').val() + '<span style="font-size: 14px"> (' + data[0].day + ')</h2><hr><p><b>Entry:</b> ' + data[0].entry + '</p><p><b>Queue jump:</b> ' + data[0].queuejump + '</p><br><p><i>Guestlist closes at ' + data[0].closing + '</i></p>'); }, dataType: "json" }); }); $('#club').change(function(event) { $.ajax({ type: "POST", url: "http://www.guestvibe.com/wp-content/themes/yasmin/guestvibe/eventinfo.php", data: $(this).serialize(), success: function(data) { $('#rightbox_inside').hide().html('<h2>' + $('#club').val() + '<span style="font-size: 14px"> (' + data[0].day + ')</h2><hr><p><b>Entry:</b> ' + data[0].entry + '</p><p><b>Queue jump:</b> ' + data[0].queuejump + '</p><br><p><i>Guestlist closes at ' + data[0].closing + '</i></p>').fadeIn('500'); }, dataType: "json" }); }); </script> I can run alerts from the jQuery, so it is active. I've copied this as is from an old version of the website, but I've changed the file structure (through to move to WordPress) so I suspect the variables might not even be reaching eventinfo.php in the first place... index.php is in wp-content/themes/cambridge and eventinfo.php is in wp-content/themes/yasmin/guestvibe but I've tried to avoid structuring issues by referencing the URL in full. Any ideas?

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  • Problem separating C++ code in header, inline functions and code.

    - by YuppieNetworking
    Hello all, I have the simplest code that I want to separate in three files: Header file: class and struct declarations. No implementations at all. Inline functions file: implementation of inline methods in header. Code file: normal C++ code for more complicated implementations. When I was about to implement an operator[] method, I couldn't manage to compile it. Here is a minimal example that shows the same problem: Header (myclass.h): #ifndef _MYCLASS_H_ #define _MYCLASS_H_ class MyClass { public: MyClass(const int n); virtual ~MyClass(); double& operator[](const int i); double operator[](const int i) const; void someBigMethod(); private: double* arr; }; #endif /* _MYCLASS_H_ */ Inline functions (myclass-inl.h): #include "myclass.h" inline double& MyClass::operator[](const int i) { return arr[i]; } inline double MyClass::operator[](const int i) const { return arr[i]; } Code (myclass.cpp): #include "myclass.h" #include "myclass-inl.h" #include <iostream> inline MyClass::MyClass(const int n) { arr = new double[n]; } inline MyClass::~MyClass() { delete[] arr; } void MyClass::someBigMethod() { std::cout << "Hello big method that is not inlined" << std::endl; } And finally, a main to test it all: #include "myclass.h" #include <iostream> using namespace std; int main(int argc, char *argv[]) { MyClass m(123); double x = m[1]; m[1] = 1234; cout << "m[1]=" << m[1] << endl; x = x + 1; return 0; } void nothing() { cout << "hello world" << endl; } When I compile it, it says: main.cpp:(.text+0x1b): undefined reference to 'MyClass::MyClass(int)' main.cpp:(.text+0x2f): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x49): undefined reference to 'MyClass::operator[](int)' main.cpp:(.text+0x65): undefined reference to 'MyClass::operator[](int)' However, when I move the main method to the MyClass.cpp file, it works. Could you guys help me spot the problem? Thank you.

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  • Make interchangeable class types via pointer casting only, without having to allocate any new objects?

    - by HostileFork
    UPDATE: I do appreciate "don't want that, want this instead" suggestions. They are useful, especially when provided in context of the motivating scenario. Still...regardless of goodness/badness, I've become curious to find a hard-and-fast "yes that can be done legally in C++11" vs "no it is not possible to do something like that". I want to "alias" an object pointer as another type, for the sole purpose of adding some helper methods. The alias cannot add data members to the underlying class (in fact, the more I can prevent that from happening the better!) All aliases are equally applicable to any object of this type...it's just helpful if the type system can hint which alias is likely the most appropriate. There should be no information about any specific alias that is ever encoded in the underlying object. Hence, I feel like you should be able to "cheat" the type system and just let it be an annotation...checked at compile time, but ultimately irrelevant to the runtime casting. Something along these lines: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Under the hood, the factory method is actually making a NodeBase class, and then using a similar reinterpret_cast to return it as a Node<AccessorFoo>*. The easy way to avoid this is to make these lightweight classes that wrap nodes and are passed around by value. Thus you don't need casting, just Accessor classes that take the node handle to wrap in their constructor: AccessorFoo foo (NodeBase::createViaFactory()); AccessorBar bar (foo.getNode()); But if I don't have to pay for all that, I don't want to. That would involve--for instance--making a special accessor type for each sort of wrapped pointer (AccessorFooShared, AccessorFooUnique, AccessorFooWeak, etc.) Having these typed pointers being aliased for one single pointer-based object identity is preferable, and provides a nice orthogonality. So back to that original question: Node<AccessorFoo>* fooPtr = Node<AccessorFoo>::createViaFactory(); Node<AccessorBar>* barPtr = reinterpret_cast< Node<AccessorBar>* >(fooPtr); Seems like there would be some way to do this that might be ugly but not "break the rules". According to ISO14882:2011(e) 5.2.10-7: An object pointer can be explicitly converted to an object pointer of a different type.70 When a prvalue v of type "pointer to T1" is converted to the type "pointer to cv T2", the result is static_cast(static_cast(v)) if both T1 and T2 are standard-layout types (3.9) and the alignment requirements of T2 are no stricter than those of T1, or if either type is void. Converting a prvalue of type "pointer to T1" to the type "pointer to T2" (where T1 and T2 are object types and where the alignment requirements of T2 are no stricter than those of T1) and back to its original type yields the original pointer value. The result of any other such pointer conversion is unspecified. Drilling into the definition of a "standard-layout class", we find: has no non-static data members of type non-standard-layout-class (or array of such types) or reference, and has no virtual functions (10.3) and no virtual base classes (10.1), and has the same access control (clause 11) for all non-static data members, and has no non-standard-layout base classes, and either has no non-static data member in the most-derived class and at most one base class with non-static data members, or has no base classes with non-static data members, and has no base classes of the same type as the first non-static data member. Sounds like working with something like this would tie my hands a bit with no virtual methods in the accessors or the node. Yet C++11 apparently has std::is_standard_layout to keep things checked. Can this be done safely? Appears to work in gcc-4.7, but I'd like to be sure I'm not invoking undefined behavior.

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  • Dynamic positioning inside relative div

    - by ian
    I'm trying to get a color picker javascript widget working in a page with a bunch of "stuff" in it that I can't change. Some of the "stuff" is causing the color picker to appear well below the link when clicked. I've reduced it to a simple example below. <html> <head> <script type="text/javascript"> function setPos(aname,dname) { var o=document.getElementById(aname); var ol=o.offsetLeft; while ((o=o.offsetParent) != null) { ol += o.offsetLeft; } o=document.getElementById(aname); var ot=o.offsetTop + 25; while((o=o.offsetParent) != null) { ot += o.offsetTop; } document.getElementById(dname).style.left = ol + "px"; document.getElementById(dname).style.top = ot + "px"; } </script> <style> h1 {height: 50px;} #divMain {position: relative;} </style> </head> <body> <h1></h1> <div id="divMain"> <a href="#" onClick="setPos('link1','div1');return false;" name="link1" id="link1">link 1</a> <div id="div1" style="position:absolute;border-style:solid;left:200px;top:200px;">div 1</div> </div> </body> </html> What's supposed to happen is when you click "link 1", "div1" should move directly below "link 1". What actually happens is that "div 1" appears well below "link 1". If you remove position: relative; from the CSS definition for divMain, "div 1" is positioned correctly. How can I position "div 1" directly beneath "link 1" without removing position: relative;?

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  • New cast exception with VS2010/.Net 4

    - by Trevor
    [ Updated 25 May 2010 ] I've recently upgraded from VS2008 to VS2010, and at the same time upgraded to .Net 4. I've recompiled an existing solution of mine and I'm encountering a Cast exception I did not have before. The structure of the code is simple (although the actual implementation somewhat more complicated). Basically I have: public class SomeClass : ISomeClass { // Stuff } public static class ClassFactory { public static IInterface GetClassInstance<IInterface>(Type classType) { return (IInterface)Activator.CreateInstance(classType); // This throws a cast exception } } // Call the factory with: ISomeClass anInstance = ClassFactory.GetClassInstance<ISomeClass>(typeof(SomeClass)); Ignore the 'sensibleness' of the above - its provides just a representation of the issue rather than the specifics of what I'm doing (e.g. constructor parameters have been removed). The marked line throws the exception: Unable to cast object of type 'Namespace.SomeClass' to type 'Namespace.ISomeClass'. I suspect it may have something to do with the additional DotNet security (and in particular, explicit loading of assemblies, as this is something my app does). The reason I suspect this is that I have had to add to the config file the setting: <runtime> <loadFromRemoteSources enabled="true" /> </runtime> .. but I'm unsure if this is related. Update I see (from comments) that my basic code does not reproduce the issue by itself. Not surprising I suppose. It's going to be tricky to identify which part of a largish 3-tier CQS system is relevant to this problem. One issue might be that there are multiple assemblies involved. My static class is actually a factory provider, and the 'SomeClass' is a class factory (relevant in that the factories are 'registered' within the app via explicit assembly/type loading - see below) . Upfront I use reflection to 'register' all factories (i.e. classes that implement a particular interface) and that I do this when the app starts by identifying the relevant assemblies, loading them and adding them to a cache using (in essence): Loop over (file in files) { Assembly assembly = Assembly.LoadFile(file); baseAssemblyList.Add(assembly); } Then I cache the available types in these assemblies with: foreach (Assembly assembly in _loadedAssemblyList) { Type[] assemblyTypes = assembly.GetTypes(); _loadedTypesCache.AddRange(assemblyTypes); } And then I use this cache to do a variety of reflection operations, including 'registering' of factories, which involves looping through all loaded (cached) types and finding those that implement the (base) Factory interface. I've experienced what may be a similar problem in the past (.Net 3.5, so not exactly the same) with an architecture that involved dynamically creating classes on the server and streaming the compiled binary of those classes to the client app. The problem came when trying to deserialize an instance of the dynamic class on the client from a remote call: the exception said the class type was not know, even though the source and destination types were exactly the same name (including namespace). Basically the cross boundry versions of the class were not recognised as being the same. I solved that by intercepting the deserialization process and explicitly defining the deseriazation class type in the context of the local assemblies. This experience is what makes me think the types are considered mismatched because (somehow) the interface of the actual SomeClass object, and the interface of passed into the Generic method are not considered the same type. So (possibly) my question for those more knowledgable about C#/DotNet is: How does the class loading work that somehow my app thinks there are two versions/types of the interface type and how can I fit that? [ whew ... anyone who got here is quite patient .. thanks ]

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  • Need Help About Using XPathNavigator in C#?

    - by Nano HE
    Hello. My XML file as below. It mixed schema and normal elements. <?xml version="1.0" encoding="utf-8"?> <!-- R1 --> <ax:root xmlns:ax="http://amecn/software/realtime/ax"> <xsd:schema xmlns:xsd="http://www.w3.org/2001/XMLSchema"> <xsd:element name="EquipmentConstants"> <xsd:complexType> <xsd:sequence> <xsd:element minOccurs="0" maxOccurs="unbounded" ref="EquipmentConstant" /> </xsd:sequence> </xsd:complexType> <xsd:unique name="id"> <xsd:selector xpath=".//EquipmentConstant" /> <xsd:field xpath="@id" /> </xsd:unique> </xsd:element> ...... ...... </xsd:schema> <EquipmentConstants xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> <EquipmentConstant id="0"> <Name>SerialNumber</Name> <Group>SYSTEM</Group> <Data> <Value min="0" max="10000000" scale_factor="0" unit="U_NO_UNITS" permission="NolimitedAndNoChangeable" type="xsd_string" enum="" flag="0">0</Value> </Data> <Description>Serial Number</Description> </EquipmentConstant> ..... ..... </EquipmentConstants> </ax:root> My C# code as below. I want to loop the elements from <EquipmentConstants xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"> XPathDocument doc = new XPathDocument("test.xml"); XPathNavigator navigator = doc.CreateNavigator(); navigator.MoveToRoot(); // <?xml version="1.0" encoding="utf-8"?> //navigator.MoveToFirstChild(); // <!-- R1 --> // 1st, I tried to use MoveToChield(), But I failed to move there. navigator.MoveToChild("EquipmentConstants"); // Then, I also tried to use SelectSingleNode(). But I failed too. navigator.SelectSingleNode("ax/EquipmentConstants"); while (navigator.MoveToNext()) { // do something. } Could you please give me some suggestion. Thank you.

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  • sendto: Network unreachable

    - by devin
    Hello. I have two machines I'm testing my code on, one works fine, the other I'm having some problems and I don't know why it is. I'm using an object (C++) for the networking part of my project. On the server side, I do this: (error checking removed for clarity) res = getaddrinfo(NULL, port, &hints, &server)) < 0 for(p=server; p!=NULL; p=p->ai_next){ fd = socket(p->ai_family, p->ai_socktype, p->ai_protocol); if(fd<0){ continue; } if(bind(fd, p->ai_addr, p->ai_addrlen)<0){ close(fd); continue; } break; } This all works. I then make an object with this constructor net::net(int fd, struct sockaddr *other, socklen_t *other_len){ int counter; this->fd = fd; if(other != NULL){ this->other.sa_family = other->sa_family; for(counter=0;counter<13;counter++) this->other.sa_data[counter]=other->sa_data[counter]; } else cerr << "Networking error" << endl; this->other_len = *other_len; } void net::gsend(string s){ if(sendto(this->fd, s.c_str(), s.size()+1, 0, &(this->other), this->other_len)<0){ cerr << "Error Sending, " << s << endl; cerr << strerror(errno) << endl; } return; } string net::grecv(){ stringstream ss; string s; char buf[BUFSIZE]; buf[BUFSIZE-1] = '\0'; if(recvfrom(this->fd, buf, BUFSIZE-1, 0, &(this->other), &(this->other_len))<0){ cerr << "Error Recieving\n"; cerr << strerror(errno) << endl; } // convert to c++ string and if there are multiple trailing ';' remove them ss << buf; s=ss.str(); while(s.find(";;", s.size()-2) != string::npos) s.erase(s.size()-1,1); return s; } So my problem is, is that on one machine, everything works fine. On another, everything works fine until I call my server's gsend() function. In which I get a "Error: Network Unreachable." I call gercv() first before calling gsend() too. Can anyone help me? I would really appreciate it.

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  • Creating multiple heads in remote repository

    - by Jab
    We are looking to move our team (~10 developers) from SVN to mercurial. We are trying to figure out how to manage our workflow. In particular, we are trying to see if creating remote heads is the right solution. We currently have a very large repository with multiple, related projects. They share a lot of code, but pieces of the project are deployed by different teams (3 teams) independent of other portions of the code-base. So each team is working on concurrent large features. The way we currently handles this in SVN are branches. Team1 has a branch for Feature1, same deal for the other teams. When Team1 finishes their change, it gets merged into the trunk and deployed out. The other teams follow suite when their project is complete, merging of course. So my initial thought are using Named Branches for these situations. Team1 makes a Feature1 branch off of the default branch in Hg. Now, here is the question. Should the team PUSH that branch, in it's current/half-state to the repository. This will create a second head in the core repo. My initial reaction was "NO!" as it seems like a bad idea. Handling multiple heads on our repository just sounds awful, but there are some advantages... First, the teams want to setup Continuous Integration to build this branch during their development cycle(months long). This will only work if the CI can pull this branch from the repo. This is something we do now with SVN, copy a CI build and change the branch. Easy. Second, it makes it easier for any team member to jump onto the branch and start working. Without pushing to the core repo, they would have to receive a push from a developer on that team with the changeset information. It is also possible to lose local commits to hardware failure. The chances increase a lot if it's a branch by a single developer who has followed the "don't push until finished" approach. And lastly is just for ease of use. The developers can easily just commit and push on their branch at any time without consequence(as they do today, in their SVN branches). Is there a better way to handle this scenario that I may be missing? I just want a veteran's opinion before moving forward with the strategy. For bug fixes we like the general workflow of mecurial, anonymous branches that only consist of 1-2 commits. The simplicity is great for those cases. By the way, I've read this , great article which seems to favor Named branches.

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  • retrieving value from database in java

    - by Akcire Atienza
    I am making AGAIN another program that retrieves the inputted data/values of fields from the database I created. but this time, my inputted value will be coming from the JtextField I created. I wonder what's wrong in here bec when I'm running it the output is always null. in this program i will convert the inputted value of my JTextField into int. here it is: public class ButtonHandler implements ActionListener { public void actionPerformed(ActionEvent e) { if(e.getSource() == extendB) { ExtensionForm extend = new ExtensionForm(); extend.setVisible(true); } else if(e.getSource()== searchB) { //get text from the textField String guest = guestIDTF.getText(); //parse the string to integer for retrieving of data int id = Integer.parseInt(guest); GuestsInfo guestInfo = new GuestsInfo(id); Room roomInfo = new Room(id); String labels[] = {guestInfo.getFirstName()+" "+guestInfo.getLastName(),""+roomInfo.getRoomNo(),roomInfo.getRoomType(),guestInfo.getTime(),"11:00"}; for(int z = 0; z<labels.length; z++) { labelDisplay[z].setText(labels[z]); } in my second class it retrieves the inputted values of fields from the database I created here's the code: import java.sql.*; public class Room { private String roomType; private int guestID, roomNo; private Connection con; private PreparedStatement statement; public Room(){ try { Class.forName("com.mysql.jdbc.Driver"); con = DriverManager.getConnection( "jdbc:mysql://localhost:3306/3moronsdb","root",""); } catch (Exception e) { e.printStackTrace(); } } public Room(int guestsID) { this(); try{ statement = con.prepareStatement("SELECT * FROM guest WHERE guestID=?"); statement.setInt(1, guestID); ResultSet rs = statement.executeQuery(); while(rs.next()){ this.guestID = rs.getInt(1); this.roomType = rs.getString(2); this.roomNo = rs.getInt(3); } }catch(Exception e){ System.out.print(e); } } //Constructor for setting rate public Room(String roomType, int roomNo) { this(); try { statement = con.prepareStatement("Insert into room(roomType, roomNo) values(?,?)"); statement.setString(1, roomType); statement.setInt(2, roomNo); statement.executeUpdate(); } catch(Exception e) { e.printStackTrace(); return; } } //getting roomType public String getRoomType(){ return roomType; } //getting roomNo public int getRoomNo(){ return roomNo; } //getting guestID public int getGuestId(){ return guestID; } } i already insert some values in my 3moronsdb which are ( 1, Classic , 103). here's my TEST main class: public class TestMain { public static void main(String [] a){ GuestsInfo guest = new GuestsInfo(1); //note that this instantiation is the other class which i just ask the other day.. (http://stackoverflow.com/questions/12762835/retrieving-values-from-database-in-java) Room rum = new Room(1); System.out.print(rum.getRoomType()+" "+ guest.getFirstName()); } } when i'm running it it only gives me null output for the Room class but i am getting the output of the GuestsInfo class which is 'Ericka'. Can you help me guys? I know I ask this kind of problem yesterday but i really don't know what's wrong in here now..

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  • Resize AIR app window while dragging

    - by matt lohkamp
    So I've noticed Windows 7 has a disturbing tendency to prevent you from dragging the title bar of windows off the top of the screen. If you try - in this case, using an air app with a draggable area at the bottom of the window, allowing you to push the top of the window up past the screen - it just kicks the window back down far enough that the title bar is at the top of what it considers the 'visible area.' One solution would be to resize the app window as it moves, so that the title bar is always where windows wants it. How would you resize the window while you're dragging it, though? Would you do it like this? dragHitArea.addEventListener(MouseEvent.MOUSE_DOWN, function(e:MouseEvent):void{ stage.nativeWindow.height += 50; stage.nativeWindow.startMove(); stage.nativeWindow.height -= 50; }); see what's going on there? When I click, I'm doing startMove(), which is hooking into the OS' function for dragging a window around. I'm also increasing and decreasing the height of the window by 50 pixels - which should give me no net increase, right? Wrong - the first '.height +=' gets executed, but the '.height -=' after the .startMove() never runs. Why? update - If you're curious, I'm programming an air widget with fly-out menus which expand rightwards and upwards - and since those element can only be displayed within the boundaries of the application window itself (even though the window is set to be chromeless and transparent) I have to expand the application's borders to include the area that the menu 'pops up' into. In the extreme case, with the widget positioned bottom left, and the menus expanded completely across to the right side and top edge of the screen, the application area could very well cover the entire desktop. The problem is, when it's expanded like this, if the user drags it up and to the right, it causes the 'title bar' area of the application window to move above the top edge of the desktop area, where it would normally be unreachable; and Windows automatically re-positions the window back below that edge once the .startMove() operation is completed. So what I want to do is continually resize the height of the application so that the visual effect will be the same for the user, but for the benefit of the operating system the window's title bar will never be above that top boundary of the desktop area.

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  • Perl ftp question, like the previous ones ...

    - by Jerry Scott
    I need to move or copy a simple text file from one web site to another web site. I have administrator rights to both web sites. The first web site has a large data file (again, just a text file), certain records are selected and written to a team file (for entry into a tournament). Next I go through paypal and pay for the entries. The second site is for the the club running the tournament and I use IPN to return to a script on their site and if it verified, I add the team memebers into the master file for the tournament. I am limited to the ONE IPN script on the tournament site because I have a ton of other entries that come in from all over. The first site has the rosters for the state and no need to type all that data from each club, use the rosters like I use for all the non-paypal tounamenmts. I can ftp the team file to the second server and place it in the folder just like it was created from scratch from that server originally and everything should go fine but I took the examples and tried them and nothing. Here's the code section: my $custom = $in->param('custom'); my $filename = "$ENV{DOCUMENT_ROOT}/database/$custom"; my $usjochost = '208.109.14.105'; my $okserieshost = '208.109.181.196'; my $usjocuser = 'teamentry'; my $okseriesuser = 'okwaentry'; my $usjocpw = 'Password1'; my $okseriespw = 'Password1'; my $file = $custom; my $usjocpath ='/home/content/u/s/j/usjoc/html/database/'; my $okseriespath ='/home/content/o/k/s/okseries/html/database/'; $ftp = Net::FTP->new($okserieshost, Debug => 0) or die "Could not connect to '$okserieshost': $@"; $ftp->login($okseriesuser, $okseriespw) or die sprintf "Could not login: %s", $ftp->message; #$ftp->cwd(/database) or die sprintf "Could not login: %s", $ftp->message; $ftp->get($filename); #$ftp = Net::FTP->new($usjochost, Debug => 0) or die "Could not connect to '$usjochost': $@"; $ftp->quit; I NEED to READ the file on the first web site (okseries.com) and write the file on the second web site (usjoc.com). I have no problem reading and writing the file on the server, is sending the file to the second server. HELP! I'm not a genius at PERL.

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  • Undefined reference to vtable

    - by RyanG
    So, I'm getting the infamously horrible "undefined reference to 'vtable..." error for the following code (The class in question is CGameModule.) and I cannot for the life of me understand what the problem is. At first, I thought it was related to forgetting to give a virtual function a body, but as far as I understand, everything is all here. The inheritance chain is a little long, but here is the related source code. I'm not sure what other information I should provide. My code: class CGameModule : public CDasherModule { public: CGameModule(Dasher::CEventHandler *pEventHandler, CSettingsStore *pSettingsStore, CDasherInterfaceBase *pInterface, ModuleID_t iID, const char *szName) : CDasherModule(pEventHandler, pSettingsStore, iID, 0, szName) { g_pLogger->Log("Inside game module constructor"); m_pInterface = pInterface; } virtual ~CGameModule() {}; std::string GetTypedTarget(); std::string GetUntypedTarget(); bool DecorateView(CDasherView *pView) { //g_pLogger->Log("Decorating the view"); return false; } void SetDasherModel(CDasherModel *pModel) { m_pModel = pModel; } virtual void HandleEvent(Dasher::CEvent *pEvent); private: CDasherNode *pLastTypedNode; CDasherNode *pNextTargetNode; std::string m_sTargetString; size_t m_stCurrentStringPos; CDasherModel *m_pModel; CDasherInterfaceBase *m_pInterface; }; } Inherits from... class CDasherModule; typedef std::vector<CDasherModule*>::size_type ModuleID_t; /// \ingroup Core /// @{ class CDasherModule : public Dasher::CDasherComponent { public: CDasherModule(Dasher::CEventHandler * pEventHandler, CSettingsStore * pSettingsStore, ModuleID_t iID, int iType, const char *szName); virtual ModuleID_t GetID(); virtual void SetID(ModuleID_t); virtual int GetType(); virtual const char *GetName(); virtual bool GetSettings(SModuleSettings **pSettings, int *iCount) { return false; }; private: ModuleID_t m_iID; int m_iType; const char *m_szName; }; Which inherits from.... namespace Dasher { class CEvent; class CEventHandler; class CDasherComponent; }; /// \ingroup Core /// @{ class Dasher::CDasherComponent { public: CDasherComponent(Dasher::CEventHandler* pEventHandler, CSettingsStore* pSettingsStore); virtual ~CDasherComponent(); void InsertEvent(Dasher::CEvent * pEvent); virtual void HandleEvent(Dasher::CEvent * pEvent) {}; bool GetBoolParameter(int iParameter) const; void SetBoolParameter(int iParameter, bool bValue) const; long GetLongParameter(int iParameter) const; void SetLongParameter(int iParameter, long lValue) const; std::string GetStringParameter(int iParameter) const; void SetStringParameter(int iParameter, const std::string & sValue) const; ParameterType GetParameterType(int iParameter) const; std::string GetParameterName(int iParameter) const; protected: Dasher::CEventHandler *m_pEventHandler; CSettingsStore *m_pSettingsStore; }; /// @} #endif

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  • Making Visual C++ DLL from C++ class

    - by prosseek
    I have the following C++ code to make dll (Visual Studio 2010). class Shape { public: Shape() { nshapes++; } virtual ~Shape() { nshapes--; }; double x, y; void move(double dx, double dy); virtual double area(void) = 0; virtual double perimeter(void) = 0; static int nshapes; }; class __declspec(dllexport) Circle : public Shape { private: double radius; public: Circle(double r) : radius(r) { }; virtual double area(void); virtual double perimeter(void); }; class __declspec(dllexport) Square : public Shape { private: double width; public: Square(double w) : width(w) { }; virtual double area(void); virtual double perimeter(void); }; I have the __declspec, class __declspec(dllexport) Circle I could build a dll with the following command CL.exe /c example.cxx link.exe /OUT:"example.dll" /DLL example.obj When I tried to use the library, Square* square; square->area() I got the error messages. What's wrong or missing? example_unittest.obj : error LNK2001: unresolved external symbol "public: virtual double __thiscall ... Square::area(void)" (?area@Square@@UAENXZ) ADDED Following wengseng's answer, I modified the header file, and for DLL C++ code, I added #define XYZLIBRARY_EXPORT However, I still got errors. example_unittest.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __th iscall Circle::Circle(double)" (__imp_??0Circle@@QAE@N@Z) referenced in function "protected: virtual void __thiscall TestOne::SetUp(void)" (?SetUp@TestOne@@MAEXXZ) example_unittest.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __th iscall Square::Square(double)" (__imp_??0Square@@QAE@N@Z) referenced in function "protected: virtual void __thiscall TestOne::SetUp(void)" (?SetUp@TestOne@@MAEXXZ) example_unittest.obj : error LNK2001: unresolved external symbol "public: virtual double __thiscall Square::area(void)" (?area@Square@@UAENXZ) example_unittest.obj : error LNK2001: unresolved external symbol "public: virtual double __thiscall Square::perimeter(void)" (?perimeter@Square@@UAENXZ) example_unittest.obj : error LNK2001: unresolved external symbol "public: virtual double __thiscall Circle::area(void)" (?area@Circle@@UAENXZ) example_unittest.obj : error LNK2001: unresolved external symbol "public: virtual double __thiscall Circle::perimeter(void)" (?perimeter@Circle@@UAENXZ)

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  • Why wont my while loop wont take new input (c++)

    - by Van
    I've written a program to get a string input from a user and parse it into tokens and move a robot according to the input. My problem is trying to issue more than one command. The code looks like: void Navigator::manualDrive() { const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; while(true) { Navigator::parseInstruction(uinput); } } /* parseInstruction(char *c) -- parses cstring instructions received * and moves robot accordingly */ void Navigator::parseInstruction(char * c) { const int bufSize = 42; char uinput[bufSize]; char delim[] = " "; char *token; cout << "Enter your directions below: \n"; cin.ignore(); cin.getline (uinput, bufSize); token=strtok(uinput, delim); if(strcmp("forward", token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); Navigator::travel(inches); } if(strcmp("back",token) == 0) { int inches; token = strtok(NULL, delim); inches = atoi (token); double value = fabs(0.0735 * fabs(inches) - 0.0550); myRobot.backward(1/*speed*/, value/*time*/); } if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("left",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.0041 * degrees - 0.0523); myRobot.turnLeft(1/*speed*/, value/*time*/); } } if(strcmp("turn",token) == 0) { int degrees; token = strtok(NULL, delim); if(strcmp("right",token) == 0) { token = strtok(uinput, delim); degrees = atoi (token); double value = fabs(0.0041 * degrees - 0.0523); myRobot.turnRight(1/*speed*/, value/*time*/); } } if(strcmp("stop",token) == 0) { myRobot.motors(0,0); } } In the function manualDrive I have a while loop calling the function parseInstruction infinitely. The program outputs "Enter your directions below: " When I give the program instructions it executes them, and then it outputs "enter your directions below: " again and when I input my directions again it does not execute them and outputs "Enter your directions below: " instead. I'm sure this is a very simple fix I'm just very new to c++. So if you could please help me out and tell me why the program only takes the first set of directions. thanks

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  • chrome renders js different depending on the extension of the file to render [testcase included]

    - by pakore
    I was trying to implement an image panner I found here Chrome renders the same document differently depending on the extension of the file requested. I have created a test case, where it works when the file it's not named as test.xhtml You can download the test case from here Does anybody know why or how to solve it? I want my files to be .xhtml In IE and FF it works fine. Code: test.html / test.xhtml (change the name to see that works with one but not with the other). <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"/> <style type="text/css"> /*Default CSS for pan containers*/ .pancontainer { position: relative; /*keep this intact*/ overflow: hidden; /*keep this intact*/ width: 300px; height: 300px; border: 1px solid black; } </style> <script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.4.2/jquery.min.js"></script> <script type="text/javascript" src="http://www.dynamicdrive.com/dynamicindex4/imagepanner.js"></script> </head> <body> <div class="pancontainer" data-orient="center" data-canzoom="yes" style="width: 350px; height: 200px; float: left; position: relative; overflow-x: hidden; overflow-y: hidden; cursor: move; "><img src="./test_files/image.jpg" style="position: absolute; width: 700px; height: 525px; left: -175px; top: -163px; display: block;" /> </div> </body> </html>

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  • Problems with createImage(int width, int height)

    - by Jonathan
    I have the following code, which is run every 10ms as part of a game: private void gameRender() { if(dbImage == null) { //createImage() returns null if GraphicsEnvironment.isHeadless() //returns true. (java.awt.GraphicsEnvironment) dbImage = createImage(PWIDTH, PHEIGHT); if(dbImage == null) { System.out.println("dbImage is null"); //Error recieved return; } else dbg = dbImage.getGraphics(); } //clear the background dbg.setColor(Color.white); dbg.fillRect(0, 0, PWIDTH, PHEIGHT); //draw game elements... if(gameOver) { gameOverMessage(dbg); } } The problem is that it enters the if statement which checks for the Image being null, even after I attempt to define the image. I looked around, and it seems that createImage() will return null if GraphicsEnvironment.isHeadless() returns true. I don't understand exactly what the isHeadless() method's purpose is, but I thought it might have something to do with the compiler or IDE, so I tried on two, both of which get the same error (Eclipse, and BlueJ). Anyone have any idea what the source of the error is, and how I might fix it? Thanks in advance Jonathan ................................................................... EDIT: I am using java.awt.Component.createImage(int width, int height). The purpose of this method is to ensure the creation of, and edit an Image that will contain the view of the player of the game, that will later be drawn to the screen by means of a JPanel. Here is some more code if this helps at all: public class Sim2D extends JPanel implements Runnable { private static final int PWIDTH = 500; private static final int PHEIGHT = 400; private volatile boolean running = true; private volatile boolean gameOver = false; private Thread animator; //gameRender() private Graphics dbg; private Image dbImage = null; public Sim2D() { setBackground(Color.white); setPreferredSize(new Dimension(PWIDTH, PHEIGHT)); setFocusable(true); requestFocus(); //Sim2D now recieves key events readyForTermination(); addMouseListener( new MouseAdapter() { public void mousePressed(MouseEvent e) { testPress(e.getX(), e.getY()); } }); } //end of constructor private void testPress(int x, int y) { if(!gameOver) { gameOver = true; //end game at mousepress } } //end of testPress() private void readyForTermination() { addKeyListener( new KeyAdapter() { public void keyPressed(KeyEvent e) { int keyCode = e.getKeyCode(); if((keyCode == KeyEvent.VK_ESCAPE) || (keyCode == KeyEvent.VK_Q) || (keyCode == KeyEvent.VK_END) || ((keyCode == KeyEvent.VK_C) && e.isControlDown()) ) { running = false; //end process on above list of keypresses } } }); } //end of readyForTermination() public void addNotify() { super.addNotify(); //creates the peer startGame(); //start the thread } //end of addNotify() public void startGame() { if(animator == null || !running) { animator = new Thread(this); animator.start(); } } //end of startGame() //run method for world public void run() { while(running) { long beforeTime, timeDiff, sleepTime; beforeTime = System.nanoTime(); gameUpdate(); //updates objects in game (step event in game) gameRender(); //renders image paintScreen(); //paints rendered image to screen timeDiff = (System.nanoTime() - beforeTime) / 1000000; sleepTime = 10 - timeDiff; if(sleepTime <= 0) //if took longer than 10ms { sleepTime = 5; //sleep a bit anyways } try{ Thread.sleep(sleepTime); //sleep by allotted time (attempts to keep this loop to about 10ms) } catch(InterruptedException ex){} beforeTime = System.nanoTime(); } System.exit(0); } //end of run() private void gameRender() { if(dbImage == null) { dbImage = createImage(PWIDTH, PHEIGHT); if(dbImage == null) { System.out.println("dbImage is null"); return; } else dbg = dbImage.getGraphics(); } //clear the background dbg.setColor(Color.white); dbg.fillRect(0, 0, PWIDTH, PHEIGHT); //draw game elements... if(gameOver) { gameOverMessage(dbg); } } //end of gameRender() } //end of class Sim2D Hope this helps clear things up a bit, Jonathan

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  • What makes a Winform position initially stale?

    - by msorens
    The code below demonstrates a very simple problem; I am hoping that I am just missing a setting that someone might be able to reveal. Goal (1) Launch main winform (MainForm). (2) Press button to display secondary winform (ShadowForm) that is semi-transparent and should exactly overlay MainForm. What Actually Happens Scenario 1: Launch main winform then press button: ShadowForm displays with correct size but incorrect location, lower and to the right (as if it was cascaded). Press button to close ShadowForm again. Press button once more to reopen ShadowForm and now it is in the correct position, covering MainForm. Scenario 2: Launch main winform, move it around, then press button: ShadowForm displays with correct size but incorrect location (where the MainForm was before moving it). Press button to close; press again to reopen and now ShadowForm is in the correct position. using System; using System.Windows.Forms; namespace LocationTest { static class Program { static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); Application.Run(new MainForm()); } } public class MainForm : Form { ShadowForm shadowForm = new ShadowForm(); Button button1 = new Button(); System.ComponentModel.IContainer components = null; public MainForm() { this.SuspendLayout(); this.button1.Location = new System.Drawing.Point(102, 44); this.button1.Size = new System.Drawing.Size(75, 23); this.button1.Text = "button1"; this.button1.Click += new System.EventHandler(this.button1_Click); this.ClientSize = new System.Drawing.Size(292, 266); this.Controls.Add(this.button1); this.ResumeLayout(false); } private void button1_Click(object sender, EventArgs e) { if (shadowForm.Visible) { shadowForm.Hide(); } else { shadowForm.Size = Size; // this always works shadowForm.Location = Location; // this fails first time, but works second time! shadowForm.Show(); } } protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } } public class ShadowForm : Form { private System.ComponentModel.IContainer components = null; public ShadowForm() { this.SuspendLayout(); this.BackColor = System.Drawing.Color.Black; this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None; this.Opacity = 0.5; this.Click += new System.EventHandler(this.ShadowForm_Click); this.ResumeLayout(false); } private void ShadowForm_Click(object sender, EventArgs e) { Hide(); } protected override void Dispose(bool disposing) { if (disposing && (components != null)) { components.Dispose(); } base.Dispose(disposing); } } }

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  • Best practices for displaying large number of images as thumbnails in c#

    - by andySF
    I got to a point where it's very difficult to get answers by debugging and tracing object, so i need some help. What I'm trying to do: A history form for my screen capture pet project. The history must list all images as thumbnails (ex: picasa). What I've done: I created a HistoryItem:UserControl. This history item has a few buttons, a check box, a label and a picture box. The buttons are for delete/edit/copy image. The check box is used for selecting one or more images and the label is for some info text. The picture box is getting the image from a public property that is a path and a method creates a proportional thumbnail to display it when the control has been loaded. This user control has two public events. One for deleting the image and one for bubbling the events for mouse enter and mouse leave trough all controls. For this I use EventBroadcastProvider. The bubbling is useful because wherever I move the mouse over the control, the buttons appear. The dispose method has been extended and I manually remove the events. All images are loaded by looping a xml file that contains the path of all images. For each image in this XML I create a new HitoryItem that is added (after a little coding to sort and limit the amount of images loaded) to a flow layout panel. The problem: When I lunch the history form, and the flow layout panel is populated with my HistoryItem custom control, my memory usage increases drastically.From 14Mb to around 100MB with 100 images loaded. By closing the history form and disposing whatever I could dispose and even trying to call GC.Collect() the memory increase remain. I search for any object that could not be disposed properly like an image or event but wherever I used them they are disposed. The problem seams to be from multiple sources. One is that the events for bubbling are not disposing properly, and the other is from the picture box itself. All of this i could see by commenting all the code to a limited version when only the custom control without any image processing and even events is loaded. Without the events the memory consumption is reduced by axiomatically 20%. So my real question is if this logic, flow layout panels and custom controls with picture boxes, is the best solution for displaying large amounts of images as thumbnails. Thank you!

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  • How do I get around this lambda expression outer variable issue?

    - by panamack
    I'm playing with PropertyDescriptor and ICustomTypeDescriptor (still) trying to bind a WPF DataGrid to an object, for which the data is stored in a Dictionary. Since if you pass WPF DataGrid a list of Dictionary objects it will auto generate columns based on the public properties of a dictionary (Comparer, Count, Keys and Values) my Person subclasses Dictionary and implements ICustomTypeDescriptor. ICustomTypeDescriptor defines a GetProperties method which returns a PropertyDescriptorCollection. PropertyDescriptor is abstract so you have to subclass it, I figured I'd have a constructor that took Func and an Action parameters that delegate the getting and setting of the values in the dictionary. I then create a PersonPropertyDescriptor for each Key in the dictionary like this: foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } The problem is that each property get's its own Func and Action but they all share the outer variable s so although the DataGrid autogenerates columns for "ID","FirstName","LastName", "Age", "Gender" they all get and set against "Gender" which is the final resting value of s in the foreach loop. How can I ensure that each delegate uses the desired dictionary Key, i.e. the value of s at the time the Func/Action is instantiated? Much obliged. Here's the rest of my idea, I'm just experimenting here these are not 'real' classes... // DataGrid binds to a People instance public class People : List<Person> { public People() { this.Add(new Person()); } } public class Person : Dictionary<string, object>, ICustomTypeDescriptor { private static PropertyDescriptorCollection descriptors; public Person() { this["ID"] = "201203"; this["FirstName"] = "Bud"; this["LastName"] = "Tree"; this["Age"] = 99; this["Gender"] = "M"; } //... other ICustomTypeDescriptor members... public PropertyDescriptorCollection GetProperties() { if (descriptors == null) { var propList = new List<PropertyDescriptor>(); foreach (string s in this.Keys) { var descriptor = new PersonPropertyDescriptor( s, new Func<object>(() => { return this[s]; }), new Action<object>(o => { this[s] = o; })); propList.Add(descriptor); } descriptors = new PropertyDescriptorCollection(propList.ToArray()); } return descriptors; } //... other other ICustomTypeDescriptor members... } public class PersonPropertyDescriptor : PropertyDescriptor { private Func<object> getFunc; private Action<object> setAction; public PersonPropertyDescriptor(string name, Func<object> getFunc, Action<object> setAction) : base(name, null) { this.getFunc = getFunc; this.setAction = setAction; } // other ... PropertyDescriptor members... public override object GetValue(object component) { return getFunc(); } public override void SetValue(object component, object value) { setAction(value); } }

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  • Const-correctness semantics in C++

    - by thirtythreeforty
    For fun and profit™, I'm writing a trie class in C++ (using the C++11 standard.) My trie<T> has an iterator, trie<T>::iterator. (They're all actually functionally const_iterators, because you cannot modify a trie's value_type.) The iterator's class declaration looks partially like this: template<typename T> class trie<T>::iterator : public std::iterator<std::bidirectional_iterator_tag, T> { friend class trie<T>; struct state { state(const trie<T>* const node, const typename std::vector<std::pair<typename T::value_type, std::unique_ptr<trie<T>>>>::const_iterator& node_map_it ) : node{node}, node_map_it{node_map_it} {} // This pointer is to const data: const trie<T>* node; typename std::vector<std::pair<typename T::value_type, std::unique_ptr<trie<T>>>>::const_iterator node_map_it; }; public: typedef const T value_type; iterator() =default; iterator(const trie<T>* node) { parents.emplace(node, node->children.cbegin()); // ... } // ... private: std::stack<state> parents; // ... }; Notice that the node pointer is declared const. This is because (in my mind) the iterator should not be modifying the node that it points to; it is just an iterator. Now, elsewhere in my main trie<T> class, I have an erase function that has a common STL signature--it takes an iterator to data to erase (and returns an iterator to the next object). template<typename T> typename trie<T>::iterator trie<T>::erase(const_iterator it) { // ... // Cannot modify a const object! it.parents.top().node->is_leaf = false; // ... } The compiler complains because the node pointer is read-only! The erase function definitely should modify the trie that the iterator points to, even though the iterator shouldn't. So, I have two questions: Should iterator's constructors be public? trie<T> has the necessary begin() and end() members, and of course trie<T>::iterator and trie<T> are mutual friends, but I don't know what the convention is. Making them private would solve a lot of the angst I'm having about removing the const "promise" from the iterator's constructor. What are the correct const semantics/conventions regarding the iterator and its node pointer here? Nobody has ever explained this to me, and I can't find any tutorials or articles on the Web. This is probably the more important question, but it does require a good deal of planning and proper implementation. I suppose it could be circumvented by just implementing 1, but it's the principle of the thing!

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