I've been using it here and there in place of named tuples and data-only classes. It is very convenient. I had a project where I had to connect to a data sour

I've been using it here and there in place of named tuples and data-only classes. It is very convenient. I had a project where I had to connect to a data source and serialize some data. When I needed to add an attribute all I had to do was add it to two places: the class itself, and the @classmethod constructor. So in this case I got the serialization for free, but that's all I was using. In reality I also got __repr__, __cmp__, etc, etc for free too, I just wasn't using it. Serialization was free because attr.asdict() knows which attributes are attr.ib() attributes. @attr.s() class Foo: bar = attr.ib() spam = attr.ib() eggs = attr.ib() # added this line @classmethod def from_something_else(cls, x): return cls( bar=x.bar.name, spam=x.spam, eggs=x.get_eggs().blah(), # and this line ) with open('blah.json', 'w') as fout: json.dump(fout, attr.asdict(o)) # got serialization for free