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  • C++ vs. C++/CLI: Const qualification of virtual function parameters

    - by James McNellis
    [All of the following was tested using Visual Studio 2008 SP1] In C++, const qualification of parameter types does not affect the type of a function (8.3.5/3: "Any cv-qualifier modifying a parameter type is deleted") So, for example, in the following class hierarchy, Derived::Foo overrides Base::Foo: struct Base { virtual void Foo(const int i) { } }; struct Derived : Base { virtual void Foo(int i) { } }; Consider a similar hierarchy in C++/CLI: ref class Base abstract { public: virtual void Foo(const int) = 0; }; ref class Derived : public Base { public: virtual void Foo(int i) override { } }; If I then create an instance of Derived: int main(array<System::String ^> ^args) { Derived^ d = gcnew Derived; } it compiles without errors or warnings. When I run it, it throws the following exception and then terminates: An unhandled exception of type 'System.TypeLoadException' occurred in ClrVirtualTest.exe Additional information: Method 'Foo' in type 'Derived'...does not have an implementation. That exception seems to indicate that the const qualification of the parameter does affect the type of the function in C++/CLI (or, at least it affects overriding in some way). However, if I comment out the line containing the definition of Derived::Foo, the compiler reports the following error (on the line in main where the instance of Derived is instantiated): error C2259: 'Derived': cannot instantiate abstract class If I add the const qualifier to the parameter of Derived::Foo or remove the const qualifier from the parameter of Base::Foo, it compiles and runs with no errors. I would think that if the const qualification of the parameter affects the type of the function, I should get this error if the const qualification of the parameter in the derived class virtual function does not match the const qualification of the parameter in the base class virtual function. If I change the type of Derived::Foo's parameter from an int to a double, I get the following warning (in addition to the aforementioned error, C2259): warning C4490: 'override': incorrect use of override specifier; 'Derived::Foo' does not match a base ref class method So, my question is, effectively, does the const qualification of function parameters affect the type of the function in C++/CLI? If so, why does this compile and why are there no errors or warnings? If not, why is an exception thrown?

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  • Configuring FluentNHibernate to use multiple databases in .net

    - by Miral
    I am using c#.net and we are using nhibernate. It was fine until i was connecting to a single database. Now in the same project i am suppose to use multiple database, how can this be achived. Configuration of the nhibernate is lies in web/app.config file. How to specify multiple connection string over there and how to create multiple session factories.

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  • Python XMLRPC with concurrent requests

    - by MattB
    I'm looking for a way to prevent multiple hosts from issuing simultaneous commands to a Python XMLRPC listener. The listener is responsible for running scripts to perform tasks on that system that would fail if multiple users tried to issue these commands at the same time. Is there a way I can block all incoming requests until the single instance has completed?

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  • Queuing asynchronous HTTP file uploads

    - by David Parunakian
    Is there a way to queue file uploads without resorting to Flash or Silverlight, just with cleverly used forms and JavaScript? Note that the upload should be executed asynchronously. By "queuing" uploads I mean that if the user tries to upload multiple files, they should not be transferred simultaneously, but rather one at a time, in a single HTTP connection.

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  • How can I query Google Spreadsheets API with a string value?

    - by ColinM
    I am using Zend_Gdata_SpreadsheetsListQuery. In PHP my query is: "confirmation=$confirmation" The problem is that $confirmation = 'AB-CD-EFG-012345'; Apparently the hyphens are causing problems with the query and the exception thrown is: Uncaught exception 'Zend_Gdata_App_HttpException' with message 'Expected response code 200, got 400 Parse error: Invalid token encountered' How can I quote or escape the value to not cause parse errors? Single quotes cause the same error, double quotes don't throw errors but there are no results to match.

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  • MDI Child form over a graphics

    - by Poco
    How to show a MDI child form over a graphics control (created from a Panel's CreateGraphics method, for instance) in a MDI Parent control. The MDI Parent graphics control gets over the MDI Child form.

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  • java interfaces

    - by Codenotguru
    write an interface with one method,two classes that implement the interface, and a main method with an array holding an instance from both classes.Using this array variable call the method in a foreach loop.This is a interview question in java anybody?

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  • Hibernate persist order

    - by user213855
    Hi there! I have a question about how Hibernate persists entity relations. Let's say I have an entity A that has a relation with entity B and another one with entity C. I create an A instance and populate it with new instances of B and C. When I persist A I need C to be persisted previous to B. Is there any way of doing this? Thanks a lot.

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  • How to launch git bash window with particular working directory using a script?

    - by holocronweaver
    How can I launch a new Git Bash window with a specified working directory using a script (either bash or Windows batch)? My goal is to launch multiple Git Bash windows from a single script, each Bash terminal set to a different working directory. This way I can quickly get to work after booting computer instead of having to open Git Bash windows and navigating each one to the correct working directory.

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  • Java OCR package

    - by pstanton
    what is the best OCR package you've used with java? I need to parse mainly numbers in a single font and am looking for a well architected, lite weight library to use. thanks.

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  • Optimum size of transaction in Postgres?

    - by Joe
    I'm running a process that does a lot of updates ( 100,000) to a table. I have the choice between putting all the updates in a single transaction or committing transactions every 1000 or so. Ignore for the moment the case where a transaction fails and is aborted. I'm interested in the best size of transaction for memory and speed efficiency.

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  • Python (Django). Store telnet connection

    - by Shamanu4
    Hello. I am programming web interface which communicates with cisco switches via telnet. I want to make such system which will be storing one telnet connection per switch and every script (web interface, cron jobs, etc.) will have access to it. This is needed to make a single query queue for each device and prevent huge cisco processor load caused by several concurent telnet connections. How do I can do this?

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  • MacRuby + Interface Builder: How to display, then close, then display a window again

    - by Derick Bailey
    I'm a complete n00b with MacRuby and Cocoa, though I've got more than a year of Ruby experience, so keep that in mind when answering - I need lots of details and explanation. :) I've set up a simple project that has 2 windows in it, both of which are built with Interface Builder. The first window is a simple list of accounts using a table view. It has a "+" button below the table. When I click the + button, I want to show an "Add New Account" window. I also have an AccountsController < NSWindowController and a AddNewAccountController class, set up as the delegates for these windows, with the appropriate button click methods wired up, and outlets to reference the needed windows. When I click the "+" button in the Accounts window, I have this code fire: @add_account.center @add_account.display @add_account.makeKeyAndOrderFront(nil) @add_account.orderFrontRegardless this works great the first time I click the + button. Everything shows up, I'm able to enter my data and have it bind to my model. however, when I close the add new account form, things start going bad. if I set the add new account window to release on close, then the second time I click the + button, the window will still pop up but it's frozen. i can't click any buttons, enter any data, or even close the form. i assume this is because the form's code has been released, so there is no message loop processing the form... but i'm not entirely sure about this. if i set the add new account window to not release on close, then the second time i click the + button, the window shows up fine and it is usable - but it still has all the data that i had previously entered... it's still bound to my previous Account class instance. what am I doing wrong? what's the correct way to create a new instance of the Add New Account form, create a new Account model, bind that model to the form and show the form, when I click the + button on the Accounts form? ... this is all being done on OSX 10.6.6, 64bit, with XCode 3.2.4

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  • Serving wildcard subdomains from the mulitple servers.

    - by user489176
    I have a web application to which I want users to login only through their unique sub-domain (the sub-domain will be chosen at signup). So that I can scale the application across a number of servers, what would be the best way to set up Apache to always serve the same subdomains from the same server? For instance: matt.yyy.com, helen.yyy.com, terry.yyy.com are always served from server with ip of xxx.xxx.xxx.xxx suzi.yyy.com, fred.yyy.com, tom.yyy.com are always served from server with ip of xxx.xxx.xxx.xxx

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  • ruby class collections

    - by poseid
    how does this work? in irb: >> class A >> b = [1, 2,3] >> end => [1, 2, 3] Is b an instance variable? class variable? how would I access b from outside the class? Is it used for meta-programming?

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  • Is there anyway to turn off the url "cliking" sound in IE using html, javascript, or flash?

    - by Anthony
    I have a flash application written in action script 2, and at one point it makes multiple back-to-back JavaScript requests using getUrl(). They have to be done as separate requests because IE had a limit on the length of a single request, and fails silently if that limit is passed. When ever this happens, if the user has their sound turned on there is a barrage of "click click click".

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  • Clean up upon the kill signal

    - by Begui
    How do you handle clean up when the program receives a kill signal? For instance, there is an application I connect to that wants any third party app (my app) to send a finish command. What is the best say to send that finish command when my app has been destroyed with a kill -9?

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  • Filling own template files

    - by Azat
    What is the best way to fill a template file with variables, which are collected from a Windows Form or Web Page. I want to create a wizard program that collects some data from user, for instance, reportname, reporttype, etc. and I need to create then some xml files (templates) with these variables inserted.

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  • Enumerating and using wmp visualizers

    - by monoceres
    Hi! I want to use the systems available windows media player visualizers in my app. Apperently visualizers expose an IWMPEffects interface to the world. My question is how do I enumerate and create instances to the available visualizers on my system? Probably it's just a process of getting the cslid of the visualizers and then create the instance with CoCreateInstance. However I have no idea how to get these clsid's! Thanks!

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