Entry

Equivalent of enum

Jul 5th, 2000 10:02
Nathan Wallace, Hans Nowak, Snippet 225, Fred L. Drake

"""
Packages: basic_applications.enumeration
"""
"""
> Is there an equivalent for enumerated types in Python?
  I've appended a little code I wrote for this; I like it because the
  numeric values are hidden and the printed values are symbolic.
  If you store this code as enum.py, use it like this:
>>> import enum
>>> myenum = enum.enumeration(['Foo', 'Bar'], 'myenum')
>>> # You can now "import myenum" elsewhere in the application
... print myenum.Bar
myenum.Bar
>>> L = [myenum.Bar, myenum.Foo]
>>> L.sort()
>>> print L
[myenum.Foo, myenum.Bar]
i
  Enjoy!
"""
"""Simple enumeration support."""
def enumeration(names, modname):
    import new
    mod = new.module(modname)
    ord = 0
    for name in names:
        setattr(mod, name, _EnumItem(name, modname, ord))
        ord = ord + 1
    import sys
    sys.modules[modname] = mod
    return mod
class _EnumItem:
    def __init__(self, name, modname, ord):
        self.name = "%s.%s" % (modname, name)
        self.modname = modname
        self.ord = ord
    def __repr__(self):
        return self.name
    def __cmp__(self, other):
        rc = cmp(self.modname, other.modname)
        if not rc:
            rc = cmp(self.ord, other.ord)
        return rc
# Fred's example, pasted and twiddled by PSST :)
myenum = enumeration(['Foo', 'Bar'], 'myenum')
print myenum.Bar
# myenum.Bar
L = [myenum.Bar, myenum.Foo]
L.sort()
print L
# [myenum.Foo, myenum.Bar]