dynamic binding

The property of {object-oriented programming} languages where

the code executed to perform a given operation is determined

at run-time from the {class} of the operand(s) (the receiver

of the message). There may be several different classes of

objects which can receive a given message. An expression may

denote an object which may have more than one possible class

and that class can only be determined at run-time. New

classes may be created that can receive a particular message,

without changing (or recompiling) the code which sends the

message. An class may be created that can receive any set of

existing messages.

{C::} implements dynamic binding using "{virtual member

function}s".

One important reason for having dynamic binding is that it

provides a mechanism for selecting between alternatives which

is arguably more robust than explicit selection by

conditionals or {pattern matching}. When a new {subclass} is

added, or an existing subclass changes, the necessary

modifications are localised: you don't have incomplete

conditionals and broken patterns scattered all over the

program.

See {overloading}.