How to tackle this nasty map

[jeet232]

Can someone pls tell me what is the exact way of stroing user-defined objects in stl map??

I've a class: Parent
I derive two classes Child1 & Child2 from it

now I declare my map as: map<Parent*, Parent*> mymap;

what i need is that while storing child1/child2, i'll static_cast both to Parent & store in.
and at find time, do the reverse static_cast & get original object.

PLS help me solving it.
I doubt if I can store pointers in map or not.
But which operators to overload in Parent class or whereelse?

I've searched net but got more confused. please help.

[JosAH]

Have a look at the 'double dispatch' or the 'visitor' pattern. Visiting a parent pointer
reveils which one you're dealing with: a child1 or child2 which, I believe is exaclty
what you want.

kind regards,

Jos

[jeet232]

Hi Jos,
thanks for the reply but that doesn't solve my problem,

I'm looking at basic level that how to use a map with user-defined objects

Regards
Jeet

[JosAH]

Hi Jos,
thanks for the reply but that doesn't solve my problem,

I'm looking at basic level that how to use a map with user-defined objects

Regards
Jeet

You may not realize it (yet?) but that simple Visitor pattern *does* solve your
problem in a neat way. Have a look in the C/C++ Articles section: WFC wrote a
nice article about it; or ask our friend Google ...

kind regards,

Jos

[weaknessforcats]

[jeet232]
what i need is that while storing child1/child2, i'll static_cast both to Parent & store in.
and at find time, do the reverse static_cast & get original object.
[/quote]

Generally, if you cast in C++ as part of your normal coding it means a) you are calling a relic C function that maybe has void* arguments, or b) your C++ design is screwed up. That is, if you have to tell a C++ compiler what the type is, then you have a problem.

C++ casts are intended to get you out of bad situations and are not to be just one of the daily activities.