Re: map allocator

From:
"Igor Tandetnik" <itandetnik@mvps.org>
Newsgroups:
microsoft.public.vc.stl
Date:
Wed, 28 Jan 2009 07:46:26 -0500
Message-ID:
<OvpOyZUgJHA.1288@TK2MSFTNGP02.phx.gbl>
"Mycroft Holmes" <m.holmes@nospam.it> wrote in message
news:ubMvZiTgJHA.4868@TK2MSFTNGP05.phx.gbl

Per 23.1.8, the last argument should be an allocator whose value
type is the same as container's value type - in this case,
pair<const double, int>.


Thanks for your answer.
So in principle, should I do this?

typedef std::map<double, int, std::less<double> >::value_type
USUAL_VALUE_TYPE;
std::map<double, int, std::less<double>,
MYALLOCATOR<USUAL_VALUE_TYPE> > m;


Well, I guess you could, but I don't see why you can't just write

std::map<double, int, std::less<double>,
 MYALLOCATOR<std::pair<const double, int> > m;

After all, you obviously don't feel that you have to give the third
parameter the same treatment:

typedef std::map<double, int>::key_type USUAL_KEY_TYPE;
std::map<double, int, std::less<USUAL_KEY_TYPE> > m;

What, in your opinion, makes the allocator parameter so special?
--
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    Igor Tandetnik

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