Template dependant argument

[Kofr]

#include <iostream>

template<class T1>
struct MyStruct {
    typedef T1 type;
    T1 data;
}

int main()
{
MyStruct<int> myData;
    MyStruct<myData::type> myDataTyped;
}

how to make MyStruct<myData::type> myDataTyped; to work?

[A Former User]

Hi!

template<class T1>
struct MyStruct {
    using t1_type = T1;
    T1 data;
};

// ...

MyStruct<int> myData;
MyStruct<decltype(myData)::t1_type> myDataTyped;

myDataTyped.data = 666;

[Kofr]

@Wieland said in Template dependant argument:

decltype(myData)

what does decltype(myData) returns so we can access its type member?

[A Former User]

@Kofr The type of myData is MyStruct<int>, thus decltype(myData) yields MyStruct<int>. See also: decltype specifier.

[Chris Kawa]

Since both variables are supposed to be of the same type it can even be shortened as

MyStruct<int> myData;
decltype(myData) myDataTyped;