TITLE: non-member functions improve encapsulation 

(Source: Scott Meyers in C/C++ Users Journal, Feb 2000)

Scott has an interesting article in print which advocates
that non-member non-friend functions improve encapsulation
for classes. He uses the following algorithm to determine
where a function f gets placed:

	if (f needs to be virtual)
   	    make f a member function of C;
	else if (f is operator>> or
         	operator<<)
	{
	   make f a non-member function;
	   if (f needs access to non-public
	       members of C)
	      make f a friend of C;
	}
	else if (f needs type conversions
	         on its left-most argument)
	{
	   make f a non-member function;
	   if (f needs access to non-public
	       members of C)
	      make f a friend of C;
	}
	else if (f can be implemented via C's
	         public interface)
	   make f a non-member function;
	else
	   make f a member function of C;

His definition of encapsulation involves the number
of functions which are impacted when private data
members are changed.

For more details in the full article see:

http://www.cuj.com/archive/1802/feature.html



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