Did you mean? in Python

didyoumean-excepthook.py

#!/usr/bin/env python

from re import search
from itertools import chain

# levenshtein
def distance(x, y):
    if not len(x): return len(y)
    if not len(y): return len(x)
    return min(distance(x[1:], y[1:]) + (x[0] != y[0]), distance(x[1:], y) + 1, distance(x, y[1:]) + 1)

import sys
def didyoumean(exc_type, value, traceback, excepthook=sys.excepthook):
    if issubclass(exc_type, AttributeError):
        terms = search("'(\w+)' object has no attribute '(\w+)'", value.message)
        if terms:
            type_name, attr = terms.groups()
            type_obj = next((t for t in 
                             chain(traceback.tb_frame.f_locals.values(),
                                   traceback.tb_frame.f_globals.values())
                             if type_name == type(t).__name__), None)
            if type_obj:
                candidate = min(dir(type_obj), key=lambda x: distance(attr, x))
                value = AttributeError(value.message + 
                          '\nMaybe you meant: {}.{}'.format(type_name, candidate))
    return excepthook(exc_type, value, traceback)
sys.excepthook = didyoumean

class Foo(object):
    def bar(self): 
        pass

if __name__ == '__main__':
    foo = Foo()
    foo.baz

didyoumean-getattr.py

#!/usr/bin/env python

# levenshtein
def distance(x, y):
    if not len(x): return len(y)
    if not len(y): return len(x)
    return min(distance(x[1:], y[1:]) + (x[0] != y[0]), distance(x[1:], y) + 1, distance(x, y[1:]) + 1)

class Foo(object):
    def bar(self): 
        pass
    def __getattr__(self, attr):
        if not attr.startswith('__'):
            candidate = min(dir(self), key=lambda x: distance(attr, x))
            raise AttributeError('Did you mean? .{}'.format(candidate))

if __name__ == '__main__':
    foo = Foo()
    foo.baz