Re: typedef for template
On 26-Jul-11 3:27 AM, Venkat S wrote:
Hi,
I've searched and not found any reference for this, so I thought
it's ok to post.
template<typename T> class Foo { ... };
template<typename X> class Bar {
typedef Foo<X> Foo; // is this a legal c++ construct?
Foo fooObj;
};
Considering the reuse of the symbol 'Foo', as a type-definition, was a typo (which is quite reasonable since otherwise you could have stated the problem without using templates), yes, you can do the above. In fact, this is a well-known workaround for absence of template typedefs support in C++ i.e. you can't do:
template <typename T>
class Foo {};
template <typename T>
typedef Foo<T> mytype; //error
Above looks pretty useless, but consider having more parameters to the template and you wanting to create a type definition with only fewer parameters. For example:
template <typename T, typename U>
class Foo {};
template <typename U>
typedef Foo<int, U> mytype; //error
You'd have to use a class like 'Bar' above to be able to create the type-definition 'mytype'.
Thanks and regards,
Abhishek Padmanabh
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