CODEWITHSUNDEEP
c++templatesc++11variadic-templates
Aleph
Aleph

Reputation: 1373

Default template parameter syntax

my question may look strange for many of you and I am really sorry for that.

As I can remember, I managed few years ago to define a class with a default template parameter such that the syntax 

Foo<> f;

can be replaced by

Foo f;

However, I cannot remember how I did that. I thought Foo class was defined with variadic templates and the default template parameter was an integer value (SIZE) but I don't manage to reproduce the target syntax.

Does anybody know how to do that? If it was just a dream, I'm really sorry!

EDIT: well, as far as I can remember, the base of the trick was to redefine

template<int SIZE=0>
class Foo;

with some variadic templates. But I am aware that my question is strange and that it is probably impossible to obtain such a syntax... :)

Upvotes: 0

Views: 64

Answers (2)

Guillaume Racicot
Guillaume Racicot

Reputation: 41750

A nice solution would be to define an alias to you type.

template<std::size_t size = 0>
struct Foo {
   // ...
};

using DefaultFoo = Foo<>;

You can't have the same name though...

Upvotes: 1

πάντα ῥεῖ
πάντα ῥεῖ

Reputation: 1

You probably want something like 

template<size_t SIZE = 0>
struct Foo {
   // ...
};

See Demo

Reducing that to 

Foo f;

isn't possible though.

Upvotes: 1

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