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Polymorphism in C++
...ecific code selected?
Run time means the compiler must generate code for all the types the program might handle while running, and at run-time the correct code is selected (virtual dispatch)
Compile time means the choice of type-specific code is made during compilation. A consequence of this: say...
The model used to open the store is incompatible with the one used to create the store
...el select your new version of data model for current data model
THAT'S NOT ALL ) You should perform so called "light migration".
Go to your AppDelegate and find where the persistentStoreCoordinator is being created
Find this line if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteS...
What are the correct version numbers for C#?
...enough); released with .NET 1.1 and VS2003 (April 2003). First version to call Dispose on IEnumerators which implemented IDisposable. A few other small features.
C# 2.0 released with .NET 2.0 and VS2005 (November 2005). Major new features: generics, anonymous methods, nullable types, iterator blocks...
How can I check if a file exists in Perl?
...mething exists at given path using the -e file-test operator.
print "$base_path exists!\n" if -e $base_path;
However, this test is probably broader than you intend. The code above will generate output if a plain file exists at that path, but it will also fire for a directory, a named pipe, a syml...
Is if(items != null) superfluous before foreach(T item in items)?
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@CodeInChaos: Do you typically find that the speed of enumerating an empty sequence is the performance bottleneck in your program?
– Eric Lippert
Jun 23 '11 at 15:19
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The type 'string' must be a non-nullable type in order to use it as parameter T in the generic type
...
Use string instead of string? in all places in your code.
The Nullable<T> type requires that T is a non-nullable value type, for example int or DateTime. Reference types like string can already be null. There would be no point in allowing things like ...
Dynamically load a JavaScript file
How can you reliably and dynamically load a JavaScript file? This will can be used to implement a module or component that when 'initialized' the component will dynamically load all needed JavaScript library scripts on demand.
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How do I check if an object has a specific property in JavaScript?
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I'm really confused by the answers that have been given - most of them are just outright incorrect. Of course you can have object properties that have undefined, null, or false values. So simply reducing the property check to typeo...
javascript scroll event for iPhone/iPad?
... onscroll only after you've stopped scrolling.
The usual way of installing the handler works e.g.
window.addEventListener('scroll', function() { alert("Scrolled"); });
// or
$(window).scroll(function() { alert("Scrolled"); });
// or
window.onscroll = function() { alert("Scrolled"); };
// etc...
Combine --user with --prefix error with setup.py install
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