Re: [Boost-users] [bind] Member fn has defeated me

From: BRIDGES Dick (Dick.Bridges_at_[hidden])
Date: 2005-10-06 15:07:57

> -----Original Message-----
> From: boost-users-bounces_at_[hidden] 
> [mailto:boost-users-bounces_at_[hidden]] On Behalf Of Simon Buchan
> Sent: Wednesday, October 05, 2005 9:49 PM
> To: boost-users_at_[hidden]
> Subject: Re: [Boost-users] [bind] Member fn has defeated me
> 
> 
> BRIDGES Dick wrote:
> <snip>
> > 
<snip>
> You find it mysterious because it's not even slightly common 
> outside of 
> functional languages.  (I hope Boost can change this).  
> Basicly: bind is 
> a function that creates a function (sortof) from a function and 
> arguments.  Confused?  Don't worry, that's normal.  Essentially:
> 
> 	bind(&X::f, &x, _1);
> 
> is the same as:
> 
> 	f_result_type bound_f(f_arg1_type arg1)
> 	{	return x.f(arg1);
> 	}
> 
> 	// ...
> 
> 	&bound_f
> 
> but with less hassles (ie. x can be local)

If I could start with a "bound" x, I probably wouldn't have so much
trouble with the concept.  I get confused when trying to deal with the
implied 'this' when starting from the bind(&X::f, _1, _2) form.  In the
current case [i.e., void f(bool)], I think _2 represents the bool
parameter and can't figure out how to express the unbound 'this'.
Clearly there is an error in my understanding of the underlying concept.