Re: class *a = new ?;

From: (Pascal J. Bourguignon)
Mon, 28 Sep 2009 13:51:53 +0200
SG <> writes:

On 28 Sep., 13:14, feribiro <> wrote:


could you tell me please how it is possible to pass the type of a
class to a function as a parameter, and then initiate a new class of
that type?

class A {...}
class B : public A {...}
class C : public A {...}

void Main()

void Create(??? param)
 A *a = new ??param??;
 delete a;

Thank you very much

You cannot do this dynamically like in other languages which keep
enough meta data about classes in memory for "reflection" (I'm
thinking of Java in this case) -- at least not without getting your
hands dirty (building registries, registering types, etc by yourself).

Well this can be done easily enough with boost::lambda.
Or somewhat less easily by defining factory functions.

typedef A* (*factory)();
A* makeInstance_B(){ return new B(); }
A* makeInstance_C(){ return new C(); }

void Create(factory f){
     A* a=f();
     delete a;


__Pascal Bourguignon__

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