How should I expose read-only fields from Python classes?

Question

I have many different small classes which have a few fields each, e.g. this:

class Article:
    def __init__(self, name, available):
        self.name = name         


        

Answer 1

As pointed out in other answers, using a property is the way to go for read-only attributes. The solution in Chris' answer is the cleanest one: It uses the property() built-in in a straight-forward, simple way. Everyone familiar with Python will recognize this pattern, and there's no domain-specific voodoo happening.

If you don't like that every property needs three lines to define, here's another straight-forward way:

from operator import attrgetter

class Article(object):
    def __init__(self, name, available):
        self._name = name
        self.available = available
    name = property(attrgetter("_name"))

Generally, I don't like defining domain-specific functions to do something that can be done easily enough with standard tools. Reading code is so much easier if you don't have to get used to all the project-specific stuff first.