Pointer to class member as a template parameter

By : Kay
Source: Stackoverflow.com
Question!

I want to use a pointer to a class member as a template parameter as in:

template <class Class, class Result, Result Class::*Member>
struct MyStruct {
    // ...
};

Using this struct like MyStruct<SomeClass, SomeResult, &SomeClass::value> variable works just fine, but I don't like that I have to specify SomeClass and SomeResult.

I would like to use MyStruct<&SomeClass::value> variable if that is possible, but without losing the ability to pass any class and have any result type.

I tried the following, but the syntax is illegal:

template <class Class, class Result>
template <Result Class::*Member>
struct MyStruct {
    // ...
};

error: too many template-parameter-lists

I tried using a helper function (that does actually work in Clang but is refused by GCC):

template <class Class, class Result>
static constexpr auto makeMyStruct(Result Class::*member) ->
MyStruct<Class, Result, member> {
    // ...
}

error: use of parameter `member' outside function body
error: template argument 3 is invalid

Is it possible to have a simple MyStruct<&SomeClass::value>, and if so, how?

Related question that did not solve my question:

By : Kay


Answers

Make your result class a child of your template class. assuming the pointer member is an object of your result class in public or whatever, you can access any objects by doing something like this

template 
By : Shawn


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