Re: iterator (adaptor) mysteries

David Abrahams <>
7 Oct 2006 11:39:58 -0400
"albrecht.fritzsche" <> writes:

One final question, though (even though it might belong
not into this general ng): what was the rational behind
the naming of the core operations for the facade? Currently
I have to look the names up all the time (equal instead of
operator==, dereference instead of operator*, ...)

Among other reasons, the idea is for the library user to write the
minimal operations that express the iterator's semantics, with no
boilerplate. That means, for example, not having to remember the
return type of operator++. If you write operator++ to express
increment, the framework has no opportunity to intercede and add the
boilerplate. The current design gives the framework a chance to be
smart about the actual presentation of the iterator interface and also
transform the semantics you provide if necessary, while still allowing
you to override its decision by writing any of those iterator
operations directly, as members.

All that said, it's a design tradeoff. Not being able to remember the
names of the core operations is a reasonable consideration that didn't
occur to us when we designed the library.

Dave Abrahams
Boost Consulting

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