Auto __repr__ method

Question

I want to have simple representation of any class, like { property = value }, is there auto __repr__?

Answer 1

Well, I played a little bit with other answers and got a very pretty solution:

class data:
    @staticmethod
    def repr(obj):
        items = []
        for prop, value in obj.__dict__.items():
            try:
                item = "%s = %r" % (prop, value)
                assert len(item) < 20
            except:
                item = "%s: <%s>" % (prop, value.__class__.__name__)
            items.append(item)

        return "%s(%s)" % (obj.__class__.__name__, ', '.join(items))

    def __init__(self, cls):
        cls.__repr__ = data.repr
        self.cls = cls

    def __call__(self, *args, **kwargs):
        return self.cls(*args, **kwargs)

You use it as a decorator:

@data
class PythonBean:
    def __init__(self):
        self.int = 1
        self.list = [5, 6, 7]
        self.str = "hello"
        self.obj = SomeOtherClass()

and get a smart __repr__ out of the box:

PythonBean(int = 1, obj: , list = [5, 6, 7], str = 'hello')

This works with any recursive classes, including tree structures. If you try to put a self-reference in the class self.ref = self, the function will try (successfully) to work it out for about a second.

Of course, always mind your boss - mine would not like such a syntax sugar ))