Re: dynamic_cast is ugly!
On 8 mar, 18:51, "Daniel T." <danie...@earthlink.net> wrote:
On Mar 8, 5:08 am, James Kanze <james.ka...@gmail.com> wrote:
Dynamic_cast has its place in good OO design; it just
shouldn't be abused.
Just like goto? :-)
No. Goto never has its place.
I don't agree that dynamic_cast has its place in *good* OO
design, but it does have its place.
You're obviously using a different definition of OO than I am,
then. Generally speaking, IMHO you should access the object
through defined interfaces; whether they are in the concrete
class, or in an abstract base class, isn't that important in the
absolute, but there will definitely be cases where a concrete
class will want to implement an extended interface. In an ideal
world, in such cases, you wouldn't loose the type, and you'd
always have access to the extended interface. Practically
speaking, however, there are cases where the object will be
passed through generic layers which do loose the type. Being
able to do so is a fundamental part of OO.
Think for a moment about Smalltalk---the granddaddy of OO
languages. Where everything was an Object, and containers only
contained Object. Of course, you didn't need dynamic_cast,
because there was no static typing to begin with. Now, it may
not be OO---in fact, according to most OO proponents, it goes
against OO---but I sort of like static type checking. As long
as I have the flexibility to work around it in cases where the
design forces a loss of the original type.
--
James Kanze (GABI Software) email:james.kanze@gmail.com
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