Re: [Boost-users] Trouble with template on boost::function and boost::bind

Subject: Re: [Boost-users] Trouble with template on boost::function and boost::bind
From: 平芜泫 (airyai_at_[hidden])
Date: 2012-03-11 11:17:21

Ah, yes, it really works if I explicitly provide the template parameters.
What a pity that the extremely beautiful code like f(boost::bind) is not
supported!

Anyway, it's ok to write something like p<string, string>(boost::bind(f,
_1, _2)), which is far better than
p(boost::function<void(string,string)>(boost::bind(f, _1, _2)).

Thanks for your help!

2012/3/11 Jeffrey Lee Hellrung, Jr. <jeffrey.hellrung_at_[hidden]>

> On Sat, Mar 10, 2012 at 11:56 PM, pwx <airyai_at_[hidden]> wrote:
>
>> I tried to create a template function that receives boost::function as
>> parameter. Say like this:
>>
>> template <typename T1, typename T2>
>> void proc(const boost::function<void(const T1&, T2&)> &p) {
>> // ...
>> }
>>
>> void f(const string& s1, string&s2) {
>> // ...
>> }
>>
>> Everything goes ok when I called proc( boost::function<void(const
>> string&, string&)>(f) ). But when I try this:
>>
>> proc(boost::bind(f, _1, _2));
>>
>> The compiler refused with the error:
>>
>> no matching function for call to
>> ‘proc(boost::_bi::bind_t<boost::_bi::unspecified, F,
>> boost::_bi::list2<boost::arg<1>, boost::arg<2> > >)’
>>
>> Anyway to fulfill this design purpose? Thanks.
>>
>
> Explicitly provide the template parameters? E.g.,
>
> proc< std::string, std::string >(boost::bind(f, _1, _2));
>
> There's really no way for the compiler to figure out what T1 and T2 should
> be without your help. Or maybe your proc should really be declared like
>
> template< class F > void proc(F const & f);
>
> ?
>
> Or maybe you can provide the above overload of proc and have its body
> provide the explicit template parameters to the original overload of proc
> for you?
>
> Just some ideas.
>
> - Jeff
>
>
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-- 
平芜尽处是春山，行人更在春山外。泫，落水成泪。