Re: [boost] Re: Recovering a function object after bind

From: Victor A. Wagner, Jr. (vawjr_at_[hidden])
Date: 2002-07-10 00:08:37

good, bad, or otherwise, for_each returns a copy of the functor.
we aren't questioning any algorithm, just for_each, and it IS defined.
I think, perhaps, you've read more into 'hazards of stateful functors' than 
is deserved.
At Tuesday 2002/07/09 17:48, you wrote:
>"Sean Parent" <sparent_at_[hidden]> wrote in message
>news:B950C3ED.12F58%sparent_at_adobe.com...
> > I'm trying to use bind with for_each but I need a copy of the bound
> > function object back after for_each. I've tried using boost::ref(f) but
> > that just gives me a compiler error (CW 7.2) that the result type isn't
> > defined (apparently on the wrapped reference.
> > [...]
>
>I can only assume that f below is a stateful functor, and you want f
>after it's been modified by for_each?  If so, the problem is that f
>is stateful. ;)  Apparently, stateful functors are bad, because there
>is no guarantee that they won't get copied an arbitrary number of
>times during use in an STL algorithm.  So, the safe thing to do is
>to only store references in a functor.  Now that the actual data is
>outside the functor anyway, you should have no trouble returning it.
>
>Dave
>
>
>
>
>
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Victor A. Wagner Jr.      http://rudbek.com
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