Re: deep copy of a polymorphic object with only a base ptr?
Hi!
jacek.dziedzic@gmail.com schrieb:
So, the bottom line is -- how do I deep copy an object of one of the
derived classes, whilst
only having the base class pointer to the instance I want to copy?
The standard solution is to extend the base class interface:
class Base
{
protected:
virtual Base* doClone() const =0;
public:
Base* clone() const { return doClone(); }
};
class Dev1 : public Base
{
protected:
virtual Dev1* doClone() const
{ return new Dev1(*this); }
public:
Dev1* clone() const { return doClone(); }
};
Then you can "clone" objects:
Base* const b1 = new Dev1;
Base* const b2 = b1->clone();
Also, both the base classes and the derived classes do not have
(user-defined) copy ctors,
since they are almost-POD and I'm satisfied with the memberwise copy
construction. Is this
compiler-generated copy ctor safe to use here?
The generated copy ctor is defined as memberwise copy. It should not
only be fine in your case, but it is usually a good choice.
HTH,
Frank
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