#!/usr/bin/env python
__version__ = "1.0"
"""OverloadedAccessors.py
This recipe presents an ideom for simplified accessors, that combines
typical getter and setter functionality of an attribute into a single
overloaded method, that instead of getATTRIBUTE and setATTRIBUTE can
now just be called ATTRIBUTE. When called without arguments it acts as
a getter and retrieves the attribute's value. When called with
arguments, the attribute is set to this value.
Keywords: accessor, getter, setter, overload, read/only attribute,
unique value, default argument
"""
omitted=[] # omitted contains an exclusive unique value
class Person:
def __init__(self, givenName, name):
self._givenName=givenName
self._name=name
# read write accessor
def givenName(self, value=omitted):
if value is not omitted: # check for exclusive unique value
self._givenName=value
return self._givenName
# read only accessor
def name(self):
return self._name
print ("The special unique value has the id %s. No other Python object is "
"identical (unsing the 'is' operator) to it.\n" % id(omitted))
p=Person('Ulrich', 'Hoffmann')
print p.givenName(), p.name() # Read attributes through accessors
print p.givenName('Ulrich Ernst') # Write attribute through accessor
print p.givenName(), p.name()
try:
print p.name("") # Read/only accessor
except TypeError:
print "I cannot set the value of 'name' in object %s. This is expected." % p
