Simple "ToStringBuilder" for Python

to_string_builder.py

def to_string_builder(obj, fields, filters={}):
    return '<{name}({fields})>'.format(
        name=type(obj).__name__,
        fields=', '.join(
            '{}={!r}'.format(name, value)
                for name, value, predicate in
                    ((name, getattr(obj, name), filters.get(name)) for name in fields)
                if predicate is None or predicate(value)),
    )

class Foo:
    def __init__(self, a, b, c = None):
        self.a = a
        self.b = b
        self.c = c
    
    def __repr__(self):
        return to_string_builder(self, ('a', 'b', 'c'), {
            'c': lambda c: c is not None,
        })