Re: dynamic_cast is only casting right?

From:
"A" <a@a.a>
Newsgroups:
comp.lang.c++
Date:
Fri, 4 Jun 2010 18:17:40 +0200
Message-ID:
<hub94a$bjk$1@gregory.bnet.hr>

It's not a question of TEdit being descendant of TObject, it's whether
Sender IS_A TEdit.


OK when you want me to paste full code I also did:

if (Sender->ClassNameIs("TEdit"))
    {
    try {
    TEdit *dEdit = dynamic_cast<TEdit *>(Sender);
    if (dEdit) if (dEdit->Modified) Button_Apply->Enabled = true;
    }
    catch (...) {
        //whatever
        }
    }

So there... checks if it is TEdit, catches exception (bad_cast) and NULL :)
All handled :)

The event may come from TEdit, TCheckBox and TComboBox (and nothing else) so
ClassName must be checked to determine where it came from.

You could also put in an assert:
assert(dynamic_cast<TEdit*>(Sender));
(then, you do as usual)


Yes, but no need in above case.

Just a comment: yeah, you could catch, and if things still are the way
they were when I was doing Delphi/C++ builder, you will catch
EAccessViolation ( which is equivalent to a crash, but VCL refuses to
die and stumbles on ;-) ).


Yes in this code but not in the above "complete" version I pasted. That one
will catch only bad_cast exception as this is the only exception that may
happen at that moment due to additional NULL check. I could probably also
check if exception type is std::bad_cast but I guess no need just more to
type :)
 

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