CODEWITHSUNDEEP
c++templatesvariadic-templatestemplate-specialization
Juergen
Juergen

Reputation: 3743

Specialize class template for variadic parameters

I want to specialize a class template for variadic parameters:

template <typename... Ts>
struct TypeList
{
};

template <typename T>
class Foo
{
};

//Is next "specialization" even possible?
template <typename... Ts>
class Foo<TypeList<Ts...>>
{
};

Foo<TypeList<int, int>> i1{}; // OK
Foo<int, int> i2{}; // NOK:  error: wrong number of template arguments (2, should be 1)

I want that users of Foo can choose between providing a TypeList or an explicit list of types.

Upvotes: 0

Views: 46

Answers (1)

Jarod42
Jarod42

Reputation: 218278

What you can do, to allow both syntaxs:

template <typename ... Ts>
class Foo : Foo<TypeList<Ts...>>
{
};

// Specialization
template <typename ... Ts>
class Foo<TypeList<Ts...>>
{
// ...
};

Upvotes: 2

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