Putting all methods in class definition

Question

When I use the pimpl idiom, is it a good idea to put all the methods definitions inside the class definition? For example:

// in A.h

class A {
   class impl;
   boost::scoped_ptr<impl> pimpl;
public:
   A();
   int foo();
}

// in A.cpp

class A::impl {
   // method defined in class
   int foo() {
       return 42;
   }

   // as opposed to only declaring the method, and defining elsewhere:
   float bar();
};

A::A() : pimpl(new impl) { }
int A::foo() {
   return pimpl->foo();
}

As far as I know, the only problems with putting a method definition inside a class definition is that (1) the implementation is visible in files that include the class definition, and (2) the compiler may make the method inline.

These are not problems in this case since the class is defined in a private file, and inlining has no effect since the methods are called in only one place.

The advantage of putting the definition inside the class is that you don't have to repeat the method signature.

So, is this OK? Are there any other issues to be aware of?

Answer 1

I think you answered your own question : both solutions are equivalent.

However, I wouldn't be so sure that 'inlining has no effect since the methods are called in only one place' : an additional call could exists when the functions are not inlined. But chances are that the compiler is smart enough to optimize them away from the one-line forwarding calls in the outer class.

In the end, I believe it's just a matter of taste.