C# for C++ Devs: Generics vs Templates for Primitive Types

re: C# for C++ Devs: Generics vs Templates for Primitive Types

luksan — Mon, 04 Feb 2008 19:37:22 GMT

This error is due to the compile-time check of convertibility. However, this check can be circumvented so that only run-time checking takes place by first converting your type to "object". So, return (int)(object)value; would have worked just as well.

re: C# for C++ Users: Generics vs Templates for Primitive Types

Colin Thomsen - MSFT — Tue, 03 Jul 2007 19:58:21 GMT

You're right and it does solve my problem. I was still thinking like a C++ dev where primitive types are not classes themselves.

I did a little extra reading (http://msdn2.microsoft.com/en-us/library/s1ax56ch(VS.80).aspx) and all the primitive (or simple) types are merely aliases for classes in the System namespace. For example, int is an alias for System.Int32. That class implements the IConvertible interface so I can use the constraint-based convert you list above.

Thanks for the suggestion.

re: C# for C++ Users: Generics vs Templates for Primitive Types

Alan J. McFarlane — Tue, 03 Jul 2007 16:23:16 GMT

I'm not a C++ user so I may be missing something, but your simple example can be done as follows:

static int convert(IConvertible value)

{

return value.ToInt32(null);

}

IConvertible is implemented by all the primitive types.

There's a boxing operation when calling that method (except when it's inlined by the JIT?), the following removes that:

static int convert2<T>(T value)

where T: IConvertible

{

return value.ToInt32(null);

}

Alan