CODEWITHSUNDEEP
c++templates
Roman Podolski
Roman Podolski

Reputation: 329

Using typedef of template class in another class

I got the following challenge.

I got a template class that defines a boost shared_ptr as a type.

template<typename T, int a, int b>
class AbstractSmth{

public:

typedef boost::shared_ptr< AbstractSmth > ABSTR_SMTH;

...
};

and an other also template class, in which I want to use that type. I know the following syntax works.

template<typename T, int a, int b>
class AbstractOtherThing{

public:

    typename AbstractSmth<T,a,b>::ABSTR_SMTH p_smth;

    void myFancyFunction(typename AbstractSmoother<T,a, b>::ABSTR_SMTH baz){
    ...
}

};

Is it possible to use that type as a typedef inside that class? Maybe something like this:

template<typename T, int a, int b>
class AbstractOtherThing{

public:

    using typename AbstractSmth<T,a,b>::ABSTR_SMTH;

    ABSTR_SMTH p_smth;

    void myFancyFunction(ABSTR_SMTH baz){
    ...
}

};

Best regards and happy new year!

Upvotes: 1

Views: 3247

Answers (2)

jrok
jrok

Reputation: 55395

Sure.

Oldschool:

typedef typename AbstractSmth<T,a,b>::ABSTR_SMTH ABSTR_SMTH;

C++11:

using ABSTR_SMTH = typename AbstractSmth<T,a,b>::ABSTR_SMTH;

Upvotes: 9

Jarod42
Jarod42

Reputation: 217135

You want:

typedef typename AbstractSmth<T,a,b>::ABSTR_SMTH ABSTR_SMTH;

or C++11 way:

using ABSTR_SMTH = typename AbstractSmth<T,a,b>::ABSTR_SMTH;

Upvotes: 2

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