Question

I love Haskell style pattern matching.

I have my C++ code as follows:

ObjectPtr ptr;
if(ptr.isType<Foo>()) { // isType returns a bool
  Ptr<Foo> p = ptr.convertAs<Foo>(); // convertAs returns a Ptr<Foo>
  ......
}
if(ptr.isType<Bar>()) {
  Ptr<Bar> p = ptr.convertAs<Bar>();
  ......
}

Now, are there any macros I can do define to simplify this? I have been pondering this for a while, but can’t simplify it further.

Thanks!

Answer 1

I’m assuming that your Ptr template has the concept of a NULL pointer.

ObjectPtr ptr;
if(Ptr<Foo> p = ptr.convertAs<Foo>()) { // convertAs returns a NULL pointer if the conversion can't be done.
  ......
}
if(Ptr<Bar> p = ptr.convertAs<Bar>()) {
  ......
}

Though, as others have noted, switching on type is usually a sign you’re doing something wrong in C++. You ought to consider using virtual functions instead.