Re: container within a container issue: set in the map

From:

James Kanze <james.kanze@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 19 Sep 2008 01:50:07 -0700 (PDT)

Message-ID:

<c94fe327-b388-4665-bb26-295709bb0ace@d45g2000hsc.googlegroups.com>

On Sep 19, 5:52 am, puzzlecracker <ironsel2...@gmail.com> wrote:

Guys, what is more preferable, given that I don't have access
to boost or shared pointers:

std::map<T*, std::set<T2*> * > *_myMap;

vs.

std::map<T*, std::set<T2*> > *myMap;

Notice that in the latter, containing set is not a pointer.
Could there be a drawbacks with the former, like copying over
when trying to insert elements into it?

I'll second Kai-Uwe's comments, but with regards to the question
about copying: the node based containers (list, set and map)
never copy an object once it is in the container. More
generally, check the container specifications: if insert and
erase don't invalidate references and pointers into the
container (except for references or pointers to the erased
element), then copying can't take place.

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