Question

I am working on a graph library in Python and I am defining my vetex this way:

class Vertex:
def __init__(self,key,value):
    self._key = key
    self._value = value

@property
def key(self):
    return self._key

@key.setter
def key(self,newKey):
    self._key = newKey

@property
def value(self):
    return self._value

@value.setter
def value(self,newValue):
    self.value = newValue

def _testConsistency(self,other):
    if type(self) != type(other):
        raise Exception("Need two vertexes here!")

def __lt__(self,other):
    _testConsistency(other)
    if self.index <= other.index:
        return True
    return False
......

Do I really have to define __lt__,__eq__,__ne__….all by my self? It is so verbose. Is there simpler way I can get around this?
Cheers.
Please dont use __cmp__ since it will be away in python 3.

Answer 1

functools.total_ordering can help you out here. It’s meant to be a class decorator. You define one of __lt__(), __le__(), __gt__(), or __ge__() AND __eq__ and it fills in the rest.

As a side note:

Instead of writing this

if self.index <= other.index:
    return True
return False

write this:

return self.index <= other.index

It’s cleaner that way. 🙂