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  • Some clarification on rvalue references

    - by Dennis Zickefoose
    First: where are std::move and std::forward defined? I know what they do, but I can't find proof that any standard header is required to include them. In gcc44 sometimes std::move is available, and sometimes its not, so a definitive include directive would be useful. When implementing move semantics, the source is presumably left in an undefined state. Should this state necessarily be a valid state for the object? Obviously, you need to be able to call the object's destructor, and be able to assign to it by whatever means the class exposes. But should other operations be valid? I suppose what I'm asking is, if your class guarantees certain invariants, should you strive to enforce those invariants when the user has said they don't care about them anymore? Next: when you don't care about move semantics, are there any limitations that would cause a non-const reference to be preferred over an rvalue reference when dealing with function parameters? void function(T&); over void function(T&&); From a caller's perspective, being able to pass functions temporary values is occasionally useful, so it seems as though one should grant that option whenever it is feasible to do so. And rvalue references are themselves lvalues, so you can't inadvertently call a move-constructor instead of a copy-constructor, or something like that. I don't see a downside, but I'm sure there is one. Which brings me to my final question. You still can not bind temporaries to non-const references. But you can bind them to non-const rvalue references. And you can then pass along that reference as a non-const reference in another function. void function1(int& r) { r++; } void function2(int&& r) { function1(r); } int main() { function1(5); //bad function2(5); //good } Besides the fact that it doesn't do anything, is there anything wrong with that code? My gut says of course not, since changing rvalue references is kind of the whole point to their existence. And if the passed value is legitimately const, the compiler will catch it and yell at you. But by all appearances, this is a runaround of a mechanism that was presumably put in place for a reason, so I'd just like confirmation that I'm not doing anything foolish.

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  • HTML tags in mysql text field

    - by paracaudex
    I'm creating a database with what I anticipate will be a long (perhaps several paragraphs for some tuples) attribute. I'm assigning it text instead of varchar. I have two questions: Should I give a maximum value for the text field? Is this necessary? Is it useful? Since the contents of this field will be displayed on a website in HTML, do I need to include paragraph tags for paragraph formatting when I enter records into mysql?

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  • Hidden features of PL/SQL

    - by Adam Paynter
    In light of the "Hidden features of..." series of questions, what little-known features of PL/SQL have become useful to you? Edit: Features specific to PL/SQL are preferred over features of Oracle's SQL syntax. However, because PL/SQL can use most of Oracle's SQL constructs, they may be included if they make programming in PL/SQL easier.

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  • Scrum stories and behind the scenes features

    - by James P.
    As I understand things, the Scrum backlog is composed of a series of Stories that represent something for the end user and this is further decomposed into Features. If this is the case, where does all the behind the scenes features go that aren't really linked to a story but are still useful? For example, say I'm making an application that catalogs the contents of a hard drive. A story wouldn't require it but having an md5 hash on each file would be a nice feature.

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  • IronPython overriding __setattr__ and __getattr__

    - by yodaj007
    I'm trying to implement a class in C# with a method that intercepts the Python __setattr__ and __getattr__ magic methods. I found this bug report: http://ironpython.codeplex.com/WorkItem/View.aspx?WorkItemId=8143 But that is from 2008, and nowhere can I find ICustomAttributes or PythonNameAttribute. I don't see anything useful in Interfaces.cs either. Can someone point me in the right direction?

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  • Any picture Gallery Control for .NET 1.1 in WinForms?

    - by Romias
    I need a UserControl to display pictures as a Gallery in Winforms. I have my pictures as a Image Collection but no problem to change to fit Control capabilities. It could be nice if it is for .NET 1.1 but since I'm planning to migrate all our code to 2.0 if the control is in that framework it could be useful in the future If it is free much better :) Does any of you know a control like this? Thanks!

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  • Defer Eclipse Treeviewer loading by DeferredTreeContentManager

    - by qichuan
    I understand there is an approach to defer TreeViewer loading by using DeferredTreeContentManager, learnt from this useful tutorial. However, this mechanism requires the model to implement IDeferredWorkbenchAdapter interface, which introduces problem to my legacy immutable model classes. Is it possible to use DeferredTreeContentManager without having model implementing IDeferredWorkbenchAdapter interface?

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  • a class function with if(this==NULL) test got compiled?

    - by James
    I saw this code snippet during our lab and it actually compiles in MSVC2008 and G++. void LinkList< class T ::Insert(T n) { if (this == NULL) // some code here } As far as I know the this must not be null since you cannot call a class functions in c++ if it wasn't instantiated. Is this a valid code? if so what's the reason behind and where it can be useful?

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  • TFS 2008 checks out code automatically on edit

    - by Jangwenyi
    I am working on a Visual Studio 2008 project that is already added to TFS server. I am not sure which settings and policies have been configured for the TFS (this is done by a separate dept, not developers) Every time I make an edit to a code file , the file is checked out automatically (without explicitly checking out the code file myself) Please help me locate this setting or policy because it is not very useful at the moment. Sometime you want to make a local change to try out something, and not necessarily check out the code....

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  • what standards i should follow?

    - by moon
    i know it is not a programming related question but pretty much relate to IT field. i have to write a user manual for my product, and i am searching for a standard from last three days but i didn't find any useful information, can anyone guide me what standards exists there for this purpose (User Manual Writing ) , if there are some good suggestions that will also help me! thanx

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  • C# unusual inheritance syntax w/ generics

    - by anon
    I happened upon this in an NHibernate class definition: public class SQLiteConfiguration : PersistenceConfiguration<SQLiteConfiguration> So this class inherits from a base class that is parameterized by... the derived class?   My head just exploded. Can someone explain what this means and how this pattern is useful? (This is NOT an NHibernate-specific question, by the way.)

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  • Google search ajax api is to restrictive. Any alternatives?

    - by boomhauer
    The google search ajax api is terrific, and the .net wrapper available on codeplex makes using it from a .net project very simple. However, the api itself is crippled so that it only returns 64 results per query. Not very useful for many applications. Ignoring the likely TOS problems, are there known .net libraries that can query the root google website and scrape the results into a resultset? I'm assuming this could result in much larger result counts than the ajax version enabled.

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  • Why are Vi and Emacs popular ?

    - by Teifion
    I've never learned to use Vi or Emacs yet people do use them still, despite there being other editors out there that are free and useful. What is it about these two and any others like them that means they hold appeal in the face of the newer editors?

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  • What to choose.... web service or WCF in asp.net 3.5

    - by HotTester
    The current project i am working on is extensively using web services and is made in .net 3.5. Now as we are going for implementation of second phase we are confused if we should either use WCF or web service as done previously ? Further is there anything new that can be useful and is coming up with .net 4.0 regarding web services or WCF. Thanks in advance. A good link for this is here.

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