Re: [boost] C++11 Metaprogramming

Subject: Re: [boost] C++11 Metaprogramming
From: Christopher Jefferson (chris_at_[hidden])
Date: 2012-04-02 04:47:35

On 1 Apr 2012, at 22:07, Nathan Ridge wrote:

> 
>> From a pure meta-programming perspective, I guess the only real 
>> addition is variadic templates.
>> However, there is the problem that they're fairly limited and that one 
>> may not expand them as the arguments of a non-variadic template.
> 
> I thought that was allowed. At least, GCC supports it since 4.7, and its
> error message for it in 4.6 was 
> 
> "sorry, unimplemented: cannot expand 'Args ...' into a fixed-length argument list"
> 
> which suggests the feature is not an extension.

There is a workaround for this, redirect through another layer of templates

template<template <typename...> T, typename... Args>
struct Join
{ typedef T<Args...> type; };

Chris