I would like to be able to arrange the ordering of Enum. Has somebody suggestions how this can be solved?
The following Enum meta class is using:
class EnumMeta(type):
def __new__(typ, name, bases, attrs):
cls_attrs = {}
cls_choices = []
for attr_name, value in attrs.items():
cls_attrs[attr_name] = attr_name.lower()
if not attr_name.startswith("__"):
cls_choices.append((attr_name.lower(), value))
def choices(cls):
return cls_choices
def values(cls, value=None):
if value is None:
return {choice[0]: unicode(choice[1]) for choice in cls.choices()}
elif isinstance(value, list):
return {choice[0]: unicode(choice[1]) for choice in cls.choices() if choice[0] in value}
else:
return unicode(dict(cls.choices()).get(value))
def keys(cls, nil=False):
items = [item[0] for item in cls.choices()]
if nil:
items.append('')
return items
def combined_length(cls):
return len(",".join(cls.values().keys()))
def max_length(cls):
return max(map(len, cls.values().keys()))
cls_attrs['choices'] = classmethod(choices)
cls_attrs['values'] = classmethod(values)
cls_attrs['keys'] = classmethod(keys)
cls_attrs['combined_length'] = classmethod(combined_length)
cls_attrs['max_length'] = classmethod(max_length)
return type(name, bases, cls_attrs)
An example of an Enum is as follow:
class SideHemType:
__ordering__ = ['double', 'single']
__metaclass__ = EnumMeta
Single = "Single side hem for opaque fabrics"
Double = "Double side hem for transparent fabrics"
class TestEnumOrdering:
print SideHemType.keys()
print SideHemType.values()
By printing the Enum SideHemType first Double is printed and then Single. But I would like first Single and then Double.
Your Enum loses the ordering in 3 places. First the attributes on the class body are stored in a dictionary, then you copy the items into another dictionary. Finally your values() returns a 3rd dictionary. A dictionary does not save ordering, and it is impossible to get the ordering of the attributes within the class body.
With this system the easiest is to have a variable
__ordering__ = [ 'single', 'double' ]
And make the values() return a list of tuples (like dict.items()).
class EnumMeta(type):
def __new__(typ, name, bases, attrs):
cls_attrs = {}
cls_choices = {}
for attr_name, value in attrs.items():
cls_attrs[attr_name] = attr_name.lower()
if not attr_name.startswith("__"):
cls_choices[attr_name.lower()] = value
ordering = attrs.get('__ordering__')
if ordering == None:
ordering = sorted(cls_choices.keys())
def choices(cls):
return dict(cls_choices)
def values(cls, value=None):
if value is None:
return [ (k, cls_choices[k] ) for k in ordering ]
elif not isinstance(value, basestring):
return [ (k, cls_choices[k] ) for k in value ]
else:
return unicode(cls_choices.get(value))
def keys(cls, nil=False):
items = list(ordering)
if nil:
items.append('')
return items
def combined_length(cls):
return len(",".join(cls.values().keys()))
def max_length(cls):
return max(map(len, cls.values().keys()))
cls_attrs['choices'] = classmethod(choices)
cls_attrs['values'] = classmethod(values)
cls_attrs['keys'] = classmethod(keys)
cls_attrs['combined_length'] = classmethod(combined_length)
cls_attrs['max_length'] = classmethod(max_length)
return type(name, bases, cls_attrs)
class SideHemType:
__ordering__ = ['double', 'single']
__metaclass__ = EnumMeta
Single = "Single side hem for opaque fabrics"
Double = "Double side hem for transparent fabrics"
print SideHemType.keys()
print SideHemType.values()