Re: Design issue - Container as a member of a class
On Dec 11, 3:22 pm, Juha Nieminen <nos...@thanks.invalid> wrote:
Stephen Howe wrote:
I frequently find that I have a container as a member of a
class and I wish to iterate over it.
From outside the class, you mean?
Then why not provide some suitable iterator, as well as a
begin() and end() function (might be also named otherwise,
depending on the case) in the public interface of your class?
(The iterator might by as simple as a typedef to the member
container iterator.)
It the abstraction of the class is to contain a set of elements,
this rejoins what Jeff Schwab said: don't expose the container,
implement an interface which defines your abstraction.
In such cases, using a typedef to define the iterator will
expose something of your internal implementation; whether this
is a problem worth solving or not will depend on how widely used
the class is. Otherwise, it's pretty trivial to wrap an
iterator in another, in order to give it its own type (and
possibly making it appear as e.g. a forward iterator, even if
the underlying container happens to be a vector at present). If
the issue comes up often, it wouldn't be that difficult to write
a template class to handle it, in which case, a typedef to an
instantiation of the template would do the trick.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
Conseils en informatique orient=E9e objet/
Beratung in objektorientierter Datenverarbeitung
9 place S=E9mard, 78210 St.-Cyr-l'=C9cole, France, +33 (0)1 30 23 00 34