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  • Setting CLASSPATH during runtime IKVM

    - by Ciddan
    How do I set a CLASSPATH variable during runtime while using IKVM? I've been trying to do it by using: java.lang.System.setProperty("java.class.path", "whatever"); The class I'm calling requires a configuration file in the classpath to work - and I keep getting errors that seem to indicate that it hasn't gotten its settings. Is the way I'm trying to add variable incorrect?

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  • Rails 3 Nested Forms with datamapper

    - by jens freudenau
    i have two models: class MeetingPoint include DataMapper::Resource belongs_to :profile property :id, Serial property :lat, String end and class Profile include DataMapper::Resource has n, :meeting_points property :id, Serial property :distance, Text property :created_at, DateTime property :updated_at, DateTime end Now I create a form to edit the profile and the meeting_poing: = form_for @profile do |f| = f.text_field :distance = f.fields_for :meeting_points do |ff| = ff.text_field :lat = f.submit But when I want to save the values I get always the error: "undefined method `readonly?' for ["lat", "14.000"]:Array"

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  • javaEE javax.xml.bind.MarshalException

    - by sandeep
    Hi, I am getting javax.xml.bind.MarshalException error. I am sending List from my webservice to the backingbean and I have this error. Here is my code: Errors WARNING: invocation error on ejb endpoint Login_webservice at /Login_webserviceService/Login_webservice : javax.xml.bind.MarshalException - with linked exception: [javax.xml.bind.JAXBException: class JPA.Cantable nor any of its super class is known to this context.] javax.xml.ws.WebServiceException: javax.xml.bind.MarshalException - with linked exception: [javax.xml.bind.JAXBException: class JPA.Cantable nor any of its super class is known to this context.] at com.sun.xml.ws.message.jaxb.JAXBMessage.writePayloadTo(JAXBMessage.java:325) at com.sun.xml.ws.message.AbstractMessageImpl.writeTo(AbstractMessageImpl.java:142) at com.sun.xml.ws.encoding.StreamSOAPCodec.encode(StreamSOAPCodec.java:109) at com.sun.xml.ws.encoding.SOAPBindingCodec.encode(SOAPBindingCodec.java:278) at com.sun.xml.ws.transport.http.HttpAdapter.encodePacket(HttpAdapter.java:380) at com.sun.xml.ws.transport.http.HttpAdapter.access$100(HttpAdapter.java:92) at com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:525) at com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:285) at com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:143) at org.glassfish.webservices.Ejb3MessageDispatcher.handlePost(Ejb3MessageDispatcher.java:116) at org.glassfish.webservices.Ejb3MessageDispatcher.invoke(Ejb3MessageDispatcher.java:87) at org.glassfish.webservices.EjbWebServiceServlet.dispatchToEjbEndpoint(EjbWebServiceServlet.java:196) at org.glassfish.webservices.EjbWebServiceServlet.service(EjbWebServiceServlet.java:127) at javax.servlet.http.HttpServlet.service(HttpServlet.java:847) Backing bean @WebServiceRef(wsdlLocation = "http://localhost:26565/Login_webserviceService/Login_webservice?WSDL") public String login() { System.out.println("Login Phase entered"); int result = 0; List list; List finalList = null; try { Weblogin.LoginWebserviceService service = new Weblogin.LoginWebserviceService(); Weblogin.LoginWebservice port = service.getLoginWebservicePort(); result = port.login(voterID, password); Weblogin.LoginWebservice port1 = service.getLoginWebservicePort(); list = port1.candDetails(1); finalList = list; this.setList(finalList); } catch (Exception e) { e.printStackTrace(); } if (result == 1) return "polling"; else return "login"; } Webservice public List candDetails(int pollEvent) { List resultList = null; List finalList = null; try { if (pollEvent == 1) { resultList = em.createNamedQuery("Cantable.findAll").getResultList(); finalList = resultList; } } catch (Exception e) { e.printStackTrace(); } return resultList; }

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  • How do I map common properties in NHibernate

    - by Ian Oakes
    In the database I'm working with, every table repeats the same nine columns and I don't want to have to supply the same properties in each of my entities to map these columns. I've tried adding properties to a common base class and adding them to the sub class's mapping file, but this doesn't work. I've read the documentation around inheritance mapping but this did not help. What is the best way to map columns that repeat accross multiple tables in NHibernate?

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  • In a DDD approach, is this example modelled correctly?

    - by Tag
    Just created an acc on SO to ask this :) Assuming this simplified example: building a web application to manage projects... The application has the following requirements/rules. 1) Users should be able to create projects inserting the project name. 2) Project names cannot be empty. 3) Two projects can't have the same name. I'm using a 4-layered architecture (User Interface, Application, Domain, Infrastructure). On my Application Layer i have the following ProjectService.cs class: public class ProjectService { private IProjectRepository ProjectRepo { get; set; } public ProjectService(IProjectRepository projectRepo) { ProjectRepo = projectRepo; } public void CreateNewProject(string name) { IList<Project> projects = ProjectRepo.GetProjectsByName(name); if (projects.Count > 0) throw new Exception("Project name already exists."); Project project = new Project(name); ProjectRepo.InsertProject(project); } } On my Domain Layer, i have the Project.cs class and the IProjectRepository.cs interface: public class Project { public int ProjectID { get; private set; } public string Name { get; private set; } public Project(string name) { ValidateName(name); Name = name; } private void ValidateName(string name) { if (name == null || name.Equals(string.Empty)) { throw new Exception("Project name cannot be empty or null."); } } } public interface IProjectRepository { void InsertProject(Project project); IList<Project> GetProjectsByName(string projectName); } On my Infrastructure layer, i have the implementation of IProjectRepository which does the actual querying (the code is irrelevant). I don't like two things about this design: 1) I've read that the repository interfaces should be a part of the domain but the implementations should not. That makes no sense to me since i think the domain shouldn't call the repository methods (persistence ignorance), that should be a responsability of the services in the application layer. (Something tells me i'm terribly wrong.) 2) The process of creating a new project involves two validations (not null and not duplicate). In my design above, those two validations are scattered in two different places making it harder (imho) to see whats going on. So, my question is, from a DDD perspective, is this modelled correctly or would you do it in a different way?

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  • SOLID Liskov Substitution Principle

    - by Omu
    if i have something like class square : figure {} class triangle : figure {} does that mean that i should never ever use the square and triangle classes but only refer to figure ? like never do like this: var x = new square();

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  • static readonly field initializer vs static constructor initialization

    - by stackoverflowuser
    Below are 2 different ways to initialize static readonly fields. Is there a difference between the 2 approaches? If yes, when should one be preferred over the other? class A { private static readonly string connectionString = WebConfigurationManager.ConnectionStrings["SomeConnection"].ConnectionString; } class B { private static readonly string connectionString; static B() { connectionString = WebConfigurationManager.ConnectionStrings["SomeConnection"].ConnectionString; } } Thanks.

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  • JQuery TableSorter with Pager and LightWindow problem

    - by Maxim
    Hi 2ALL... I've a tablesorter with attached pager plugin on my page with links 'Details' in the one of the cell. Links have a class='lightwindow' and after clicking is rising up a LightWindow script with a window. So it work's vell on the First Page .. when i click Next Page on SortTable.Pager and clickin on my link 'Details' it's doesnt work correctly, it looks like my links lost their class='lightwindow'. Any suggestions?

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  • siblings in jquery hide everything

    - by user2658615
    This is my html code : <div id="tabbase"> <ul> <li>a</li> <li>b</li> </ul> <div id="tabs-0"></div> <div id="tabs-1"> <div class="width50"> <h5>title1</h5> <div class="da-desc">a</div> <button>continue</button> </div> <div class="width50"> <h5>title2</h5> <div class="da-desc">b</div> <button>continue</button> </div> </div> </div> and this is CSS code : #tabbase { margin:16px; } #tabbase ul li { display:inline-block; margin:5px 0px 5px 0; background:rgb(224,224,224); padding:5px; border:1px solid rgb(153,153,153); cursor:pointer; } #tabs-0, #tabs-1 { border:1px solid rgb(153,153,153); background:rgb(255,255,255); padding:5px; margin:-5px 0 0 0; } #tabbase ul li.active { background:rgb(255,255,255) !important; } and this is jquery code : $(document).ready(function(e) { $("#tabs-1").hide(0); $("#tabbase ul li:first").addClass("active"); $("#tabbase ul li").click(function(e) { $(this).addClass("active"); $(this).siblings(this).removeClass("active"); count = $("#tabbase ul li").index(this); $('#tabs-'+count).slideDown(500).siblings(this).slideUp(500); }); }); so you can see that when you click on a tab , all tabs are gone and how can I fix this?

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  • Is this too much code for a header only library?

    - by Billy ONeal
    It seems like I had to inline quite a bit of code here. I'm wondering if it's bad design practice to leave this entirely in a header file like this: #pragma once #include <string> #include <boost/noncopyable.hpp> #include <boost/make_shared.hpp> #include <boost/iterator/iterator_facade.hpp> #include <Windows.h> #include "../Exception.hpp" namespace WindowsAPI { namespace FileSystem { class FileData; struct AllResults; struct FilesOnly; template <typename Filter_T = AllResults> class DirectoryIterator; namespace detail { class DirectoryIteratorImpl : public boost::noncopyable { WIN32_FIND_DATAW currentData; HANDLE hFind; std::wstring root; public: inline DirectoryIteratorImpl(); inline explicit DirectoryIteratorImpl(const std::wstring& pathSpec); inline void increment(); inline bool equal(const DirectoryIteratorImpl& other) const; inline const std::wstring& GetPathRoot() const; inline const WIN32_FIND_DATAW& GetCurrentFindData() const; inline ~DirectoryIteratorImpl(); }; } class FileData //Serves as a proxy to the WIN32_FIND_DATA struture inside the iterator. { boost::shared_ptr<detail::DirectoryIteratorImpl> iteratorSource; public: FileData(const boost::shared_ptr<detail::DirectoryIteratorImpl>& parent) : iteratorSource(parent) {}; DWORD GetAttributes() const { return iteratorSource->GetCurrentFindData().dwFileAttributes; }; bool IsDirectory() const { return (GetAttributes() | FILE_ATTRIBUTE_DIRECTORY) != 0; }; bool IsFile() const { return !IsDirectory(); }; bool IsArchive() const { return (GetAttributes() | FILE_ATTRIBUTE_ARCHIVE) != 0; }; bool IsReadOnly() const { return (GetAttributes() | FILE_ATTRIBUTE_READONLY) != 0; }; unsigned __int64 GetSize() const { ULARGE_INTEGER intValue; intValue.LowPart = iteratorSource->GetCurrentFindData().nFileSizeLow; intValue.HighPart = iteratorSource->GetCurrentFindData().nFileSizeHigh; return intValue.QuadPart; }; std::wstring GetFolderPath() const { return iteratorSource->GetPathRoot(); }; std::wstring GetFileName() const { return iteratorSource->GetCurrentFindData().cFileName; }; std::wstring GetFullFileName() const { return GetFolderPath() + GetFileName(); }; std::wstring GetShortFileName() const { return iteratorSource->GetCurrentFindData().cAlternateFileName; }; FILETIME GetCreationTime() const { return iteratorSource->GetCurrentFindData().ftCreationTime; }; FILETIME GetLastAccessTime() const { return iteratorSource->GetCurrentFindData().ftLastAccessTime; }; FILETIME GetLastWriteTime() const { return iteratorSource->GetCurrentFindData().ftLastWriteTime; }; }; struct AllResults : public std::unary_function<const FileData&, bool> { bool operator()(const FileData&) { return true; }; }; struct FilesOnly : public std::unary_function<const FileData&, bool> { bool operator()(const FileData& arg) { return arg.IsFile(); }; }; template <typename Filter_T> class DirectoryIterator : public boost::iterator_facade<DirectoryIterator<Filter_T>, const FileData, std::input_iterator_tag> { friend class boost::iterator_core_access; boost::shared_ptr<detail::DirectoryIteratorImpl> impl; FileData current; Filter_T filter; void increment() { do { impl->increment(); } while (! filter(current)); }; bool equal(const DirectoryIterator& other) const { return impl->equal(*other.impl); }; const FileData& dereference() const { return current; }; public: DirectoryIterator(Filter_T functor = Filter_T()) : impl(boost::make_shared<detail::DirectoryIteratorImpl>()), current(impl), filter(functor) { }; explicit DirectoryIterator(const std::wstring& pathSpec, Filter_T functor = Filter_T()) : impl(boost::make_shared<detail::DirectoryIteratorImpl>(pathSpec)), current(impl), filter(functor) { }; }; namespace detail { DirectoryIteratorImpl::DirectoryIteratorImpl() : hFind(INVALID_HANDLE_VALUE) { } DirectoryIteratorImpl::DirectoryIteratorImpl(const std::wstring& pathSpec) { std::wstring::const_iterator lastSlash = std::find(pathSpec.rbegin(), pathSpec.rend(), L'\\').base(); root.assign(pathSpec.begin(), lastSlash); hFind = FindFirstFileW(pathSpec.c_str(), &currentData); if (hFind == INVALID_HANDLE_VALUE) WindowsApiException::ThrowFromLastError(); while (!wcscmp(currentData.cFileName, L".") || !wcscmp(currentData.cFileName, L"..")) { increment(); } } void DirectoryIteratorImpl::increment() { BOOL success = FindNextFile(hFind, &currentData); if (success) return; DWORD error = GetLastError(); if (error == ERROR_NO_MORE_FILES) { FindClose(hFind); hFind = INVALID_HANDLE_VALUE; } else { WindowsApiException::Throw(error); } } DirectoryIteratorImpl::~DirectoryIteratorImpl() { if (hFind != INVALID_HANDLE_VALUE) FindClose(hFind); } bool DirectoryIteratorImpl::equal(const DirectoryIteratorImpl& other) const { if (this == &other) return true; return hFind == other.hFind; } const std::wstring& DirectoryIteratorImpl::GetPathRoot() const { return root; } const WIN32_FIND_DATAW& DirectoryIteratorImpl::GetCurrentFindData() const { return currentData; } } }}

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  • Using IoC and Dependency Injection, how do I wrap an existing implementation with a new layer of imp

    - by Dividnedium
    I'm trying to figure out how this would be done in practice, so as not to violate the Open Closed principle. Say I have a class called HttpFileDownloader that has one function that takes a url and downloads a file returning the html as a string. This class implements an IFileDownloader interface which just has the one function. So all over my code I have references to the IFileDownloader interface and I have my IoC container returning an instance of HttpFileDownloader whenever an IFileDownloader is Resolved. Then after some use, it becomes clear that occasionally the server is too busy at the time and an exception is thrown. I decide that to get around this, I'm going to auto-retry 3 times if I get an exception, and wait 5 seconds in between each retry. So I create HttpFileDownloaderRetrier which has one function that uses HttpFileDownloader in a for loop with max 3 loops, and a 5 second wait between each loop. So that I can test the "retry" and "wait" abilities of the HttpFileDownloadRetrier I have the HttpFileDownloader dependency injected by having the HttpFileDownloaderRetrier constructor take an IFileDownloader. So now I want all Resolving of IFileDownloader to return the HttpFileDownloaderRetrier. But if I do that, then HttpFileDownloadRetrier's IFileDownloader dependency will get an instance of itself and not of HttpFileDownloader. So I can see that I could create a new interface for HttpFileDownloader called IFileDownloaderNoRetry, and change HttpFileDownloader to implement that. But that means I'm changing HttpFileDownloader, which violates Open Closed. Or I could implement a new interface for HttpFileDownloaderRetrier called IFileDownloaderRetrier, and then change all my other code to refer to that instead of IFileDownloader. But again, I'm now violating Open Closed in all my other code. So what am I missing here? How do I wrap an existing implementation (downloading) with a new layer of implementation (retrying and waiting) without changing existing code? Here's some code if it helps: public interface IFileDownloader { string Download(string url); } public class HttpFileDownloader : IFileDownloader { public string Download(string url) { //Cut for brevity - downloads file here returns as string return html; } } public class HttpFileDownloaderRetrier : IFileDownloader { IFileDownloader fileDownloader; public HttpFileDownloaderRetrier(IFileDownloader fileDownloader) { this.fileDownloader = fileDownloader; } public string Download(string url) { Exception lastException = null; //try 3 shots of pulling a bad URL. And wait 5 seconds after each failed attempt. for (int i = 0; i < 3; i++) { try { fileDownloader.Download(url); } catch (Exception ex) { lastException = ex; } Utilities.WaitForXSeconds(5); } throw lastException; } }

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  • initializing variables in ActiveRecord's classes

    - by Hadi
    How to initialize variables in ActiveRecord class? Variables here is the variables that are outside the scope of database such as: class Product attr_accessor :used end I want to initially assign @used initially to false, later if some person access the product, i will change @used to true First i thought of putting @used=false in initialize method, but it does not get called.

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  • div automatically added in $item->get_description(); using simplepie

    - by Carey Estes
    I am getting a div that is appearing in the output from calling a RSS feed. It is ignoring my attempts to wrap it in a paragraph tag and pushes the data out to the div. foreach ($feed->get_items(0 , 3) as $item): $feedDescription = $item->get_content(); $image = returnImage($feedDescription); $image = scrapeImage($image); $image_url= $item->get_permalink(); $description = $item->get_description(); ?> <div class="item"> <h4><a href="<?php echo $item->get_permalink(); ?>"><?php echo $item->get_title(); ?></a></h4> <div class="image-box"><?php echo '<a href="' . $image_url . '"><img src="' . $image . '" /></a>'."\n";?></div> <p><?php echo $description ?></p> <p><a href="<?php echo $item->get_permalink(); ?>">Continue Reading</a></p> </div> <?php endforeach; ?> Here is the html output: <div class="item"> <h4><a href="#">Lorem Ipsum</a></h4> <div class="image-box"><a href="#"><img src="image.jpg"></a> </div> <p></p> <div>Lorem Ipsum description [...]</div> <p></p> <p><a href="#">Continue Reading</a></p> </div> Why does the description call add a div tag and not get wrapped in the paragraph tag?

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  • Error trying to run rails server

    - by David87
    I am trying to get a basic Rails application to run on my Mac OS X 10.6.5. I created a new app called demo (rails new demo), then went into the demo directory and tried to start the app with rails server. Here is the error message I received: "/Users/dpetrovi/.gem/ruby/1.8/gems/sqlite3-ruby-1.3.2/lib/sqlite3/sqlite3_native.bundle: [BUG] Segmentation fault ruby 1.8.7 (2010-12-23 patchlevel 330) [i686-darwin10] Abort trap" I checked bundle install in the demo folder: "Using rake (0.8.7) Using abstract (1.0.0) Using activesupport (3.0.3) Using builder (2.1.2) Using i18n (0.5.0) Using activemodel (3.0.3) Using erubis (2.6.6) Using rack (1.2.1) Using rack-mount (0.6.13) Using rack-test (0.5.6) Using tzinfo (0.3.23) Using actionpack (3.0.3) Using mime-types (1.16) Using polyglot (0.3.1) Using treetop (1.4.9) Using mail (2.2.13) Using actionmailer (3.0.3) Using arel (2.0.6) Using activerecord (3.0.3) Using activeresource (3.0.3) Using bundler (1.0.7) Using thor (0.14.6) Using railties (3.0.3) Using rails (3.0.3) Using sqlite3-ruby (1.3.2) Your bundle is complete! Use bundle show [gemname] to see where a bundled gem is installed." Ruby, RubyGems, and sqlite3 were installed using MacPorts. Then I used gem to try to install the sqlite3-ruby interface. (sudo gem install sqlite3-ruby). Here is where I first noticed something could be off: "Successfully installed sqlite3-ruby-1.3.2 1 gem installed Installing ri documentation for sqlite3-ruby-1.3.2... No definition for libversion Enclosing class/module 'mSqlite3' for class Statement not known Installing RDoc documentation for sqlite3-ruby-1.3.2... No definition for libversion Enclosing class/module 'mSqlite3' for class Statement not known " I had rails running well on my system a few months ago, so I figured maybe I had some duplicates and it was trying to use the wrong one. I ran: "for cmd in ruby irb gem rake; do which $cmd; done" and got: "/opt/local/bin/ruby /opt/local/bin/irb /opt/local/bin/gem /opt/local/bin/rake" Checking where sqlite3 also gets me: "/opt/local/bin/sqlite3" so they all seem to be in the right place. Obviously /opt/local/bin is in my system path. If I check gems server, it shows that I have installed sqlite3-ruby 1.3.2 gem. Not sure what the problem could be? I am using ruby 1.8.7 (2010-12-23 patchlevel 330) [i686-darwin10]. Macports claims this is the latest (although ive seen 1.9.1) One more thing-- in irb, I tried to check which version of sqlite3 my sqlite3-ruby is bound to, but I can only get this far: ":irb(main):001:0 require 'rubygems' = true irb(main):002:0 require 'sqlite3' /Users/dpetrovi/.gem/ruby/1.8/gems/sqlite3-ruby-1.3.2/lib/sqlite3/sqlite3_native.bundle: [BUG] Segmentation fault ruby 1.8.7 (2010-12-23 patchlevel 330) [i686-darwin10] Abort trap" Any suggestions? Im hoping I overlooked something obvious. Thanks

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  • Get preferences in AppWidget Provider

    - by Brian515
    Hi all, I seem to be having trouble reading preferences from my AppWidgetProvider class. My code works in an Activity, but it does not in an AppWidgetProvider. Here is the code I am using to read back a boolean: SharedPreferences settings = getSharedPreferences(PREFS_NAME, 0); boolean autoreplyon = settings.getBoolean("autoreplyon", false); However, I get the "The method getSharedPreferences(String, int) is undefined for the type widget" error (widget is the name of my AppWidgetProvider class). Thanks in advance for any suggestions!

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  • Define interface for loading custom UserControls through reflection

    - by Tim
    I'm loading custom user controls into my form using reflection. I would like all my user controls to have a "Start" and "End" method so they should all be like: public interface IStartEnd { void Start(); void End(); } public class AnotherControl : UserControl, IStartEnd { public void Start() { } public void End() { } } I would like an interface to load through reflection, but the following obviously wont work as an interface cannot inherit a class: public interface IMyUserControls : UserControl, IInit, IDispose { }

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  • C# monkey patching - is it possible?

    - by Adal
    Is it possible to write a C# assembly which when loaded will inject a method into a class from another assembly? If yes, will the injected method be available from languages using DLR, like IronPython? namespace IronPython.Runtime { public class Bytes : IList<byte>, ICodeFormattable, IExpressionSerializable { internal byte[] _bytes; //I WANT TO INJECT THIS METHOD public byte[] getbytes() { return _bytes; } } } I need that method, and I would like to avoid recompiling IronPython if possible.

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  • inheritance from str or int

    - by wiso
    Why I have problem creating a class the inherite from str (or also int) class C(str): def __init__(self, a, b): str.__init__(self,a) self.b = b C("a", "B") TypeError: str() takes at most 1 argument (2 given) tha same appened if I try to use int instead of str, but it works with custom classes. I need to use __new__ instead of __init__? why?

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  • Simple java syncrhonization question

    - by Misha Koshelev
    Dear All: Was wondering, which is correct: Option One class A { public void methodOne() { synchronized(this) { modifyvalue notifyAll() } } public void methodTwo() { while (valuenotmodified) { synchronized(this) { wait() } } } Option Two class A { public void methodOne() { modifyvalue synchronized(this) { notifyAll() } } public void methodTwo() { while (valuenotmodified) { synchronized(this) { wait() } } } and why? Thank you Misha

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  • How do I use accepts_nested_attributes_for? I cannot use the .build method (!)

    - by Angela
    Editing my question for conciseness and to update what I've done: How do I model having multiple Addresses for a Company and assign a single Address to a Contact, and be able to assign them when creating or editing a Contact? Here is my model for Contacts: class Contact < ActiveRecord::Base attr_accessible :first_name, :last_name, :title, :phone, :fax, :email, :company, :date_entered, :campaign_id, :company_name, :address_id, :address_attributes belongs_to :company belongs_to :address accepts_nested_attributes_for :address end Here is my model for Address: class Address < ActiveRecord::Base attr_accessible :street1, :street2, :city, :state, :zip has_many :contacts end I would like, when creating an new contact, access all the Addresses that belong to the other Contacts that belong to the Company. So here is how I represent Company: class Company < ActiveRecord::Base attr_accessible :name, :phone, :addresses has_many :contacts has_many :addresses, :through => :contacts end Here is how I am trying to create a field in the View for _form for Contact so that, when someone creates a new Contact, they pass the address to the Address model and associate that address to the Contact: <% f.fields_for :address, @contact.address do |builder| %> <p> <%= builder.label :street1, "Street 1" %> </br> <%= builder.text_field :street1 %> <p> <% end %> When I try to Edit, the field for Street 1 is blank. And I don't know how to display the value from show.html.erb. At the bottom is my error console -- can't seem to create values in the address table: My Contacts controller is as follows: def new @contact = Contact.new @contact.address.build # I GET AN ERROR HERE: says NIL CLASS @contact.date_entered = Date.today @campaigns = Campaign.find(:all, :order => "name") if params[:campaign_id].blank? else @campaign = Campaign.find(params[:campaign_id]) @contact.campaign_id = @campaign.id end if params[:company_id].blank? else @company = Company.find(params[:company_id]) @contact.company_name = @company.name end end def create @contact = Contact.new(params[:contact]) if @contact.save flash[:notice] = "Successfully created contact." redirect_to @contact else render :action => 'new' end end def edit @contact = Contact.find(params[:id]) @campaigns = Campaign.find(:all, :order => "name") end Here is a snippet of my error console: I am POSTING the attribute, but it is not CREATING in the Address table.... Processing ContactsController#create (for 127.0.0.1 at 2010-05-12 21:16:17) [POST] Parameters: {"commit"="Submit", "authenticity_token"="d8/gx0zy0Vgg6ghfcbAYL0YtGjYIUC2b1aG+dDKjuSs=", "contact"={"company_name"="Allyforce", "title"="", "campaign_id"="2", "address_attributes"={"street1"="abc"}, "fax"="", "phone"="", "last_name"="", "date_entered"="2010-05-12", "email"="", "first_name"="abc"}} Company Load (0.0ms)[0m [0mSELECT * FROM "companies" WHERE ("companies"."name" = 'Allyforce') LIMIT 1[0m Address Create (16.0ms)[0m [0;1mINSERT INTO "addresses" ("city", "zip", "created_at", "street1", "updated_at", "street2", "state") VALUES(NULL, NULL, '2010-05-13 04:16:18', NULL, '2010-05-13 04:16:18', NULL, NULL)[0m Contact Create (0.0ms)[0m [0mINSERT INTO "contacts" ("company", "created_at", "title", "updated_at", "campaign_id", "address_id", "last_name", "phone", "fax", "company_id", "date_entered", "first_name", "email") VALUES(NULL, '2010-05-13 04:16:18', '', '2010-05-13 04:16:18', 2, 2, '', '', '', 5, '2010-05-12', 'abc', '')[0m

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  • Implementing a robust async stream reader for a console

    - by Jon
    I recently provided an answer to this question: C# - Realtime console output redirection. As often happens, explaining stuff (here "stuff" was how I tackled a similar problem) leads you to greater understanding and/or, as is the case here, "oops" moments. I realized that my solution, as implemented, has a bug. The bug has little practical importance, but it has an extremely large importance to me as a developer: I can't rest easy knowing that my code has the potential to blow up. Squashing the bug is the purpose of this question. I apologize for the long intro, so let's get dirty. I wanted to build a class that allows me to receive input from a Stream in an event-based manner. The stream, in my scenario, is guaranteed to be a FileStream and there is also an associated StreamReader already present to leverage. The public interface of the class is this: public class MyStreamManager { public event EventHandler<ConsoleOutputReadEventArgs> StandardOutputRead; public void StartSendingEvents(); public void StopSendingEvents(); } Obviously this specific scenario has to do with a console's standard output. StartSendingEvents and StopSendingEvents do what they advertise; for the purposes of this discussion, we can assume that events are always being sent without loss of generality. The class uses these two fields internally: protected readonly StringBuilder inputAccumulator = new StringBuilder(); protected readonly byte[] buffer = new byte[256]; The functionality of the class is implemented in the methods below. To get the ball rolling: public void StartSendingEvents(); { this.stopAutomation = false; this.BeginReadAsync(); } To read data out of the Stream without blocking, and also without requiring a carriage return char, BeginRead is called: protected void BeginReadAsync() { if (!this.stopAutomation) { this.StandardOutput.BaseStream.BeginRead( this.buffer, 0, this.buffer.Length, this.ReadHappened, null); } } The challenging part: BeginRead requires using a buffer. This means that when reading from the stream, it is possible that the bytes available to read ("incoming chunk") are larger than the buffer. Since we are only handing off data from the stream to a consumer, and that consumer may well have inside knowledge about the size and/or format of these chunks, I want to call event subscribers exactly once for each chunk. Otherwise the abstraction breaks down and the subscribers have to buffer the incoming data and reconstruct the chunks themselves using said knowledge. This is much less convenient to the calling code, and detracts from the usefulness of my class. Edit: There are comments below correctly stating that since the data is coming from a stream, there is absolutely nothing that the receiver can infer about the structure of the data unless it is fully prepared to parse it. What I am trying to do here is leverage the "flush the output" "structure" that the owner of the console imparts while writing on it. I am prepared to assume (better: allow my caller to have the option to assume) that the OS will pass me the data written between two flushes of the stream in exactly one piece. To this end, if the buffer is full after EndRead, we don't send its contents to subscribers immediately but instead append them to a StringBuilder. The contents of the StringBuilder are only sent back whenever there is no more to read from the stream (thus preserving the chunks). private void ReadHappened(IAsyncResult asyncResult) { var bytesRead = this.StandardOutput.BaseStream.EndRead(asyncResult); if (bytesRead == 0) { this.OnAutomationStopped(); return; } var input = this.StandardOutput.CurrentEncoding.GetString( this.buffer, 0, bytesRead); this.inputAccumulator.Append(input); if (bytesRead < this.buffer.Length) { this.OnInputRead(); // only send back if we 're sure we got it all } this.BeginReadAsync(); // continue "looping" with BeginRead } After any read which is not enough to fill the buffer, all accumulated data is sent to the subscribers: private void OnInputRead() { var handler = this.StandardOutputRead; if (handler == null) { return; } handler(this, new ConsoleOutputReadEventArgs(this.inputAccumulator.ToString())); this.inputAccumulator.Clear(); } (I know that as long as there are no subscribers the data gets accumulated forever. This is a deliberate decision). The good This scheme works almost perfectly: Async functionality without spawning any threads Very convenient to the calling code (just subscribe to an event) Maintains the "chunkiness" of the data; this allows the calling code to use inside knowledge of the data without doing any extra work Is almost agnostic to the buffer size (it will work correctly with any size buffer irrespective of the data being read) The bad That last almost is a very big one. Consider what happens when there is an incoming chunk with length exactly equal to the size of the buffer. The chunk will be read and buffered, but the event will not be triggered. This will be followed up by a BeginRead that expects to find more data belonging to the current chunk in order to send it back all in one piece, but... there will be no more data in the stream. In fact, as long as data is put into the stream in chunks with length exactly equal to the buffer size, the data will be buffered and the event will never be triggered. This scenario may be highly unlikely to occur in practice, especially since we can pick any number for the buffer size, but the problem is there. Solution? Unfortunately, after checking the available methods on FileStream and StreamReader, I can't find anything which lets me peek into the stream while also allowing async methods to be used on it. One "solution" would be to have a thread wait on a ManualResetEvent after the "buffer filled" condition is detected. If the event is not signaled (by the async callback) in a small amount of time, then more data from the stream will not be forthcoming and the data accumulated so far should be sent to subscribers. However, this introduces the need for another thread, requires thread synchronization, and is plain inelegant. Specifying a timeout for BeginRead would also suffice (call back into my code every now and then so I can check if there's data to be sent back; most of the time there will not be anything to do, so I expect the performance hit to be negligible). But it looks like timeouts are not supported in FileStream. Since I imagine that async calls with timeouts are an option in bare Win32, another approach might be to PInvoke the hell out of the problem. But this is also undesirable as it will introduce complexity and simply be a pain to code. Is there an elegant way to get around the problem? Thanks for being patient enough to read all of this.

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