Re: [boost] Any interest in dynamic dispatching mechanism from & quot; interface& quot; to template functions ?

Subject: Re: [boost] Any interest in dynamic dispatching mechanism from & quot; interface& quot; to template functions ?
From: Raffi Enficiaud (raffi.enficiaud_at_[hidden])
Date: 2010-07-02 08:20:42

Larry Evans <cppljevans <at> suddenlink.net> writes:

> 
> On 07/01/10 20:30, Larry Evans wrote:
> [snip]
> This sounds something like functor in category theory:
> 
>    http://en.wikipedia.org/wiki/Functor
> 
> What you have is 2 functions:
> 
>    f_i the interface function
>    f_t the template function
> 
> and you want someway to convert a call to the f_i to f_t.
> So, given:
> 
>    t_i0 f_i(t_i1, t_i2, ..., t_in)
> 
> and:
> 
>    t_t0 f_t(t_t1, t_t2, ..., t_tn)
> 
> you want a set of conversion functions:
> 
>     t_tj c_j(t_ij)
> 
> so that you can call:
> 
>      t_t0 f_t(c_1(t_i1), c_2(t_i2), ... c_n(t_in) )
> 
> or something like that, right?
> 
> -regards,
> Larry
> 

This is the general idea, but it does not really 
coincide with the notion of mathematical functor. These are
homomorphism, which means that they preserve a mathematical
structure. Well here, there is no such kind of structure I guess.
The "objects" are here the types and their specific instance. 
Plus functors are arrows with one direction, while the c_i's 
are bidirectional (possible update of the interface parameters 
during their destruction). 

The convertors preserves composition, as functors do. So I would
think about "mapping objects" rather than functors. 

But the call 
  t_t0 f_t(c_1(t_i1), c_2(t_i2), ... c_n(t_in) )

is exactly the idea !

Kind regards,
Raffi