#!/usr/bin/env python
def enum(*sequential, **named):
# Check for duplicate keys
names = list(sequential)
names.extend(named.keys())
if len(set(names)) != len(names):
raise KeyError('Cannot create enumeration with duplicate keys!')
# Build property dict
enums = dict(zip(sequential, range(len(sequential))), **named)
if not enums:
raise KeyError('Cannot create empty enumeration')
if len(set(enums.values())) < len(enums):
raise ValueError('Cannot create enumeration with duplicate values!')
# Function to be called as fset/fdel
def err_func(*args, **kwargs):
raise AttributeError('Enumeration is immutable!')
# function to be called as fget
def getter(cls, val):
return lambda cls: val
# Create a base type
t = type('enum', (object,), {})
# Add properties to class by duck-punching
for attr, val in enums.iteritems():
setattr(t, attr, property(getter(t, val), err_func, err_func))
# Return an instance of the new class
return t()
if __name__ == "__main__":
"""A small ammount of code to demo the functionality"""
try:
print 'Creating empty enum...',
e = enum()
print 'OK!'
except KeyError as e:
print 'ERROR:', e
try:
print 'Creating enum with duplicate keys...',
e = enum('OK', 'OK', OK=2)
print 'OK!'
except KeyError as e:
print 'ERROR:', e
try:
print 'Creating enum with duplicate values...',
e = enum(OK=1, PASS=1)
print 'OK!'
except ValueError as e:
print 'ERROR:', e
try:
print 'Creating valid enum...',
e = enum('OK', 'CANCEL', 'QUIT', test=4, ok='YES')
print 'OK!'
except Exception as e:
print 'ERROR:', e
# Immutable?
try:
print 'Changing e.OK = "ASDF"...',
e.OK = 'ASDF'
print 'OK!'
except AttributeError as ex:
print 'ERROR:', ex
try:
print 'Deleting e.OK...',
del e.OK
print 'OK!'
except AttributeError as ex:
print 'ERROR:', ex
print e
print e.OK
print e.CANCEL
print e.QUIT
print e.test
print e.ok
