"""StrKeyDict always converts non-string keys to `str`

Tests for item retrieval using `d[key]` notation::

>>> d = StrKeyDict([('2', 'two'), ('4', 'four')])

>>> d['2']

'two'

>>> d[4]

'four'

>>> d[1]

Traceback (most recent call last):

...

KeyError: '1'

Tests for the `in` operator::

>>> 2 in d

True

>>> 1 in d

False

Test for item assignment using non-string key::

>>> d[0] = 'zero'

>>> d['0']

'zero'

Tests for update using a `dict` or a sequence of pairs::

>>> d.update({6:'six', '8':'eight'})

>>> sorted(d.keys())

['0', '2', '4', '6', '8']

>>> d.update([(10, 'ten'), ('12', 'twelve')])

>>> sorted(d.keys())

['0', '10', '12', '2', '4', '6', '8']

>>> d.update([1, 3, 5])

Traceback (most recent call last):

...

TypeError: 'int' object is not iterable

"""

# BEGIN STRKEYDICT

import collections

import collections.abc

class StrKeyDict(collections.UserDict): # <1>

def __init__(self, args, normalize=str, **kwargs):

super().__init__(self, *args, **kwargs)

self.normalize = normalize

def __missing__(self, key): # <2>

if self.normalize(key) == key:

raise KeyError(key)

return self[self.normalize(key)]

def __contains__(self, key):

return self.normalize(key) in self.data # <3>

def __setitem__(self, key, item):

self.data[self.normalize(key)] = item # <4>

def update(self, iterable=None, **kwds):

if iterable is not None:

if isinstance(iterable, collections.abc.Mapping): # <5>

pairs = iterable.items()

else:

pairs = ((k, v) for k, v in iterable) # <6>

for key, value in pairs:

self[key] = value # <7>

if kwds:

self.update(kwds) # <8>

# END STRKEYDICT