class attrExample(dict):
"""Example of overloading __getatr__ and __setattr__
This example creates a dictionary where members can be accessed as attributes
"""
def __init__(self, indict=None, attribute=None):
if indict is None:
indict = {}
# set any attributes here - before initialisation
# these remain as normal attributes
self.attribute = attribute
dict.__init__(self, indict)
self.__initialised = True
# after initialisation, setting attributes is the same as setting an item
def __getattr__(self, item):
"""Maps values to attributes.
Only called if there *isn't* an attribute with this name
"""
try:
return self.__getitem__(item)
except KeyError:
raise AttributeError(item)
def __setattr__(self, item, value):
"""Maps attributes to values.
Only if we are initialised
"""
if not self.__dict__.has_key('_attrExample__initialised'): # this test allows attributes to be set in the __init__ method
return dict.__setattr__(self, item, value)
elif self.__dict__.has_key(item): # any normal attributes are handled normally
dict.__setattr__(self, item, value)
else:
self.__setitem__(item, value)
if __name__ == '__main__':
example = attrExample(attribute='fish')
print example.attribute
example.fish = 'test'
print example['fish']
print example.fish
