Re: [boost] An analogue of boost.function with multiple signatures

Subject: Re: [boost] An analogue of boost.function with multiple signatures
From: Marco (mrcekets_at_[hidden])
Date: 2009-03-05 19:35:14

Hello Jiøí,
you can find two implementations of multi functions in the boost vault

msf-1.2.2.zip by Marco Costalba

and

overload-mrcec/overload-0.3.0.zip by me

About the last one you can read a tutorial here:
http://docs.google.com/Doc?id=dfxvjncs_1x6456m

Some remark:

(1) I don't know if they can interoperate with boost::lamba,
you should give it a try.

Using my implementation you can get what you're interested in
with the following code:

struct doubler
{
    template< typename T>
    T operator() (const T& x)
    {
        return x + x;
    }
};

boost::overload< std::string (std::string),
                  float (float),
                  unsigned (unsigned)
                > mf;
mf.set(doubler);
mf("ab");
mf((UINT_MAX/2)+1);
mf((UINT_MAX/2)+1.0);

(2) they are not extensions of boost function but separate libraries.

Kind regards,
Marco

On Fri, 06 Mar 2009 00:44:23 +0100, Jiøí Paleèek <jpalecek_at_[hidden]> wrote:

> Hello,
>
> I'd like to have an object similar to boost::function, but with multiple
> function signatures. Eg. something like that
>
> multifunction<std::string(std::string), float(float),  
> unsigned(unsigned)> mf;
> mf=_1 + _1; // I mean boost::lambda::_1
> mf("ab"); // should be "abab"
> mf((UINT_MAX/2)+1); // should be 0
> mf((UINT_MAX/2)+1.0); // should be UINT_MAX+1.0
>
> Would it be possible/feasible to change boost::function to allow this (as
> opposed to implementing it separately from boost::function)? Was  
> something like this even proposed before (I vaguely recall something,  
> but couldn't
> google anything useful, so I may be wrong)?
>
> Regards
>     Jiri Palecek

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