C++ Syntax - template

Question

Can't google this out so just looking for a quick answer. What this syntax means and is it standard C++?

template <class ...Options>
class list_base_hook;

The code is from boost libraries. http://www.boost.org/doc/libs/1_52_0/doc/html/intrusive/usage.html

The search keyword here is "variadic templates". It means you can pass many arguments. It is a C++11 feature, but Boost did some tricks to make that class work before C++03. — R. Martinho Fernandes, Dec 17 '12 at 13:48
See [Variadic templates](http://stackoverflow.com/questions/276188/variadic-templates). — Bo Persson, Dec 17 '12 at 13:49

ltjax · Answer 1 · 2012-12-17T16:33:28.563

10

This is a variadic template which is part of the new C++11 standard.

edited Dec 17 '12 at 16:33

answered Dec 17 '12 at 13:48

ltjax

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score 2 · Accepted Answer · answered Dec 17 '12 at 13:49

In C++11 it's a variadic template parameter.

Boost uses that syntax for "psuedo-variadic" templates from C++03 too - meaning it is a bunch typenames with defaults. Not exactly the same as C++11's variadics. Like this:

template <class opt1 = dummy, class op2 = dummy, class op3 = dummy, /* and so on up to a large N */>
class list_base_hook;

C++ Syntax - template

2 Answers2