CODEWITHSUNDEEP
c++classsystemc
Rorschach
Rorschach

Reputation: 764

C++: Typedef of template class

I'm trying to create typedef of a vector class I have. I have found similar problems on SO, but they focus on classes that are templates that accept different types of data, while my class is template based on integers.

So, my class is defined like this:

namespace sc_dt {
  template <int W> class sc_bv { ... }; //meaning systemc_bit_vector
}

And I want to use typedef so I wouldn't have to type in sc_dt:: every time. However, by using this:

typedef sc_dt::sc_bv<int> sc_vector;

I get the following error:

Type/value mismatch at argument 1 in template argument list

How do I fix this?

Upvotes: 0

Views: 914

Answers (3)

NathanOliver
NathanOliver

Reputation: 180990

namespace sc_dt {
  template <int W> class sc_bv { ... } //meaning systemc_bit_vector
}

Has a non-type template parameter. When you instantiate an object of sc_bv you need to give it an int constant like

sc_dt::sc_bv<2> foo;

As you can see that is different than

typedef sc_dt::sc_bv<int> sc_vector;

Where you gave it a type, instead of a value.

If you know what value you want to use for sc_vector then you could use

typedef sc_dt::sc_bv<the_value_that_you_want_to_use> sc_vector;

or if you just want sc_vector to be a new name for the class template then you can use an alias template like

template<int value>
using sc_vector = sc_dt::sc_bv<value>;

which then lets you use sc_vector like

sc_vector<some_value> foo;

Upvotes: 5

apple apple
apple apple

Reputation: 10614

if you do not want to type namespace sc_dt:: every time, using the namespace or 

using sc_dt::sc_bv;

Upvotes: 3

Max Langhof
Max Langhof

Reputation: 23711

typedefs can't be templated. However, usings can be (and this achieves the desired effect):

template<int W>
using sc_vector = sc_dt::sc_bv<W>;

Upvotes: 5

Related Questions