Style

It helps if you decide upon a uniform style for writing code. It's common to suggest that for all except the most trivial classes it's wise to define

• a void constructor -
• a copy constructor - to create a new object using values from an existing one. Use call-by-reference to avoid infinite recursion.
• the assignment operator - that returns a reference.

And then there's the "the rule of three" - if you write any one of a copy constructor, copy assignment operator or destructor, then you will almost certainly need to write all three for your class to function properly.

Stanley Lippman in Dr.Dobb's Journal, October 99, (p.40) noted that unnecessary definition of these functions is likely in practise to make the code bigger and/or slower - he got a 40% speed improvement by removing all 3 from a piece of code, the compiler's default alternatives being more efficient.

When deriving classes

• if using public inheritance, most base class member functions should be declared virtual to ensure that the derived class customisations will override the base class behaviour even in a context where a base class object is expected.
• use virtual inheritance if you are not especially concerned about performance or if you might use multiple inheritance later.