Delegation is an object oriented technique (also called a design pattern). Let's say you have an object x and want to change the behaviour of just one of its methods. You can create a new class that provides a new implementation of the method you're interested in changing and delegates all other methods to the corresponding method of x. The example shows a class that captures the behavior of the file and converts data from lower to uppercase.
class upcase:
def __init__(self, out):
self._out = out
def write(self, s):
self._outfile.write(s.upper())
def __getattr__(self, name):
return getattr(self._out, name)
The write() method is used in the upcase class converts the string to the uppercase before calling another method. The delegation is being given using the self.__outfile object.
