Is it possible to overload template classes in c ?-CodePudding

I'm currently creating some utilities for my projects, and I came up with the idea to replicate the C# Action class in C . As you can see in the C# documentation, the Action class can have different "overloads" with templates. It has Action, Action<T1>, Action<T1, T2\>, etc.

Is it possible to overload classes like this in C ? Or, is there any workaround?

This is an example of "pseudocode", C throws a syntax error with this:

class Action
{
    // Code
};

template<class T1>
class Action
{
    // Code
};

template<class T1, class T2>
class Action
{
    // Code
};

// etc...

So that you can call different kinds of classes depending if you input a template or not, like this:

int main()
{
    Action a1;
    Action<int> a2;
    Action<int, float> a3;
    // etc...

    return 0;
}

I tried various things, such as:

template<T1, T2>
class Action {};

template<T1, T2>
class Action<T1.> {};

template<T1, T2>
class Action<T1, T2> {};

But this does not work.

CodePudding user response：

No, classes can't be overloaded. Action in the scope can be either a single non-templated class or a single class template with a given template head (not different ones).

But, a given class template can be specialized for certain template arguments and there are variadic templates since C 11 which accept an arbitrary number of template arguments:

template<typename... Ts>
class Action { /* generic case */ };

This allows for a2 and a3 and via explicit or partial specialization they can be specialized for e.g. one or two template arguments:

template<typename T1>
class Action<T1> { /* one template argument */ };

template<typename T1, typename T2>
class Action<T1, T2> { /* two template arguments */ };

a1 can also work since C 17 via class template argument deduction (CTAD) depending on which constructors the primary class template has and/or what deduction guides are declared.

I don't have enough knowledge of C# or context to know whether this is a useful approach to take for your underlying problem though.

Also, as a side note: class and typename when introducing template parameters in the template head are synonymous. Choose class if you prefer that. There is no difference.