Re: [boost] detecting a constructor with a specific signature

Subject: Re: [boost] detecting a constructor with a specific signature
From: vicente.botet (vicente.botet_at_[hidden])
Date: 2010-01-27 12:59:43

----- Original Message ----- 
From: "Steven Watanabe" <watanabesj_at_[hidden]>
To: <boost_at_[hidden]>
Sent: Wednesday, January 27, 2010 6:32 PM
Subject: Re: [boost] detecting a constructor with a specific signature

> 
> AMDG
> 
> vicente.botet wrote:
>> "Kenny Riddile" <kfriddile_at_[hidden]> wrote:
>>   
>>> Alas, I'm using VC9.  The first declaration of select() gives me the 
>>> following error:
>>>
>>> error C2564: 'T' : a function-style conversion to a built-in type can 
>>> only take one argument
>>>     
>>
>> Hi,
>>
>> have you tried to double ()
>>
>> template< typename T >
>>  typename result< sizeof T(( make< const std::string& >(), make< Foo& >() )) >::type select( int );
>>   
> 
> That doesn't try the same constructor.
> 
> The problem is that this method requires extended SFINAE
> which VC9 doesn't support.

You are right, my proposal test if there is a constructor with an argument Foo&, isn't it?

I confirm it works for gcc-4.4.0 and fails to compile for gcc-4.3.2 and MSVC v9.

Steven, does this mean that it is possible to implement the trait with a good C++98 compiler? Or there are other things missing yet?

Thanks,
Vicente