"Peter Dimov" <pdimov@mmltd.net> wrote in message news:002101c4214f$0cfb5f30$1d00a8c0@pdimov2...
Thorsten Ottosen wrote:
Hi Peter,
[snp]
Yes, of course it is possible to reject the example. But I don't want to reject it. It's useful.
Ok. Could you present an example?
This feature of bind is used to create stateful function objects. In a "real" lambda facility it corresponds to a local static variable:
for_each( first, last, lambda(v) { static int x = 0; f(v, ++x); } );
The bind equivalent is
for_each( first, last, bind( f, _1, bind(incr, 0) ) );
ok, but couldn't incr() just be defined as 'int incr( int i ) { return i + 1; }' ? Anyway, it is not the possibility of having "local static" data in function objects we are arguing about, its about what to pass that data to.
Bind's emphasis is on usefulness, not hand-holding.
good frase :-)
Its learning curve is inherently steep and more importantly, it simply cannot be flattened by making bind less useful.
I guess the current design gives maximal power; so it it seems ok. Requering that the user calls bind( f, local_copy( i ) ) would document that the programmer knows that f takes a reference, but that it can act on a copy. However, once you know the mechanism, you would be irritated by such constraints. br Thorsten