Re: [boost] Streaming Lambda functions

From: Steven Watanabe (watanabesj_at_[hidden])
Date: 2008-07-11 14:30:58

AMDG

Robert Jones wrote:
> On Fri, Jul 11, 2008 at 7:08 PM, Steven Watanabe <watanabesj_at_[hidden]>
> wrote:
>
>   
>> The overload of operator<< for std::pair is not found by Boost.Lambda.
>>     
> This much I have discovered painfully by trial and error - the bit I don't
> understand
> is why!

There are two ways that functions can be found from within
a template.  The first is the functions which are visible at the
point where the template is defined.  Your overload of operator<<
is not declared when the Boost.Lambda stuff is included, so
it won't be found that way.

The second way is through ADL.  ADL searches /only/ in namespaces
associated with the argument types.  In this case only namespace std
is associated with the argument types, not the global namespace, so
operator<< can't be found that way either.

>  Also, it would be very handy if you can suggest a method of
> achieving the
> effect I'm looking for.
>   

There isn't a legal way.  The standard forbids adding functions
to namespace std.

In Christ,
Steven Watanabe