I've seen this in a lot of example code:
but I don't quite understand why you would default it to void?Code:template <typename T=void>
You can create a void* variable, but not a void variable, so what's going on?
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I've seen this in a lot of example code:
but I don't quite understand why you would default it to void?Code:template <typename T=void>
You can create a void* variable, but not a void variable, so what's going on?
What about:
Code:class TemplateClass {
T *test;
};
The only thing I could imagine is when T is declared as a variable like that, but then why use void* if you're using a template? Aren't void* pointers more useful in C than in C++?
Sometimes these things are used to deliberately cause compile errors in certain situations. For instance, if you want to restrict the types of template parameters which are allowed to be used. See boost::enable_ifQuote:
Originally Posted by cpjust
Hmm brewbuck may have a point. But I'd rather do that something like this:
Rather than defaulting to void and declaring a variable that wouldn't be allowed.Code:template<typename T> class SomeClass;
template<>
class SomeClass<AllowedType1> {
};
But, true, void pointers can often be avoided in C++. So the system you read it at would probably be badly designed anyway.
I think I saw it in Stroustrup's C++ book. :)Quote:
Originally Posted by EVOEx