Yet another attempt to write a useful var_dump for Python

about.py

import pprint
import logging


def about(thang):
    def shorty(x):
        if len(x) > 200:
            x = x[:200] + "..."
        return x
    if isinstance(thang, dict):
        info = dict([(x, shorty(repr(thang.get(x)))) for x in thang.keys()])
    else:
        info = dict([(x, shorty(repr(getattr(thang, x)))) for x in dir(thang)
                     if not x.startswith("_")])
    import pprint
    return pprint.pformat(info)


def _is_primitive(obj):
    return (
        isinstance(obj, int) or
        isinstance(obj, float) or
        isinstance(obj, complex) or
        isinstance(obj, str) or
        isinstance(obj, unicode) or
        isinstance(obj, bool)
    )


def dig(obj, n, hack_kv=None, base=''):
    """
    Dig through an object looking for a particular thing. I think this might
    be useful in providing arguments to mock.patch, because those things are
    always kinda non-obvious.
    """
    if n == 0:
        return
    if obj is None:
        return
    if hack_kv is None:
        # pylint: disable=function-redefined
        def hack_kv(key, strkey, subobj):
            print strkey, '=>', repr(subobj)
            return _is_primitive(subobj)
        # pylint: enable=function-redefined
    if isinstance(obj, list) or isinstance(obj, tuple):
        iterable = range(len(obj))
        selector = lambda k, obj=obj: obj[k]
        fmt = "[{0}]"
    elif isinstance(obj, dict):
        iterable = [k for k in obj.keys() if not k.startswith('__')]
        selector = lambda k, obj=obj: obj.get(k)
        fmt = '["{0}"]'
    else:
        iterable = [k for k in dir(obj) if not k.startswith('__')]
        selector = lambda k, obj=obj: getattr(obj, k)
        fmt = ".{0}"
    for k in iterable:
        if base:
            s = base + fmt.format(k)
        else:
            s = str(k)
        y = selector(k)
        if not hack_kv(k, s, y):
            try:
                dig(y, n - 1, hack_kv, s)
            except:
                pass

if __name__ == '__main__':
    # quick dumb test
    def foo(k, obj, s):
        if k != 'func_globals':
            print s, '=>', obj
    dig(sys, 3, foo)