libb.replacekey

replacekey(d, key, newval)

Context manager for temporarily patching a dictionary value.

Parameters:

• d (dict) – Dictionary to patch.

• key – Key to temporarily replace.

• newval – Temporary value to set.

Basic Usage:

>>> f = dict(x=13)
>>> with replacekey(f, 'x', 'pho'):
...     f['x']
'pho'
>>> f['x']
13

If the dict does not have the key set before, we return to that state:

>>> import os, sys
>>> rand_key = str(int.from_bytes(os.urandom(10), sys.byteorder))
>>> with replacekey(os.environ, rand_key, '22'):
...     os.environ[rand_key]=='22'
True
>>> rand_key in os.environ
False