Python equivalent of PHP's compact() and extract()

Question

compact() and extract() are functions in PHP I find tremendously handy. compact() takes a list of names in the symbol table and creates a hashtable with just their values.

Answer 1

I'm afraid there are no equivalents in Python. To some extent, you can simulate their effect using (and passing) locals:

>>> def compact(locals, *keys):
...     return dict((k, locals[k]) for k in keys)
...
>>> a = 10
>>> b = 2
>>> compact(locals(), 'a', 'b')
{'a': 10, 'b': 2}

>>> def extract(locals, d):
...     for k, v in d.items():
...         locals[k] = v
...
>>> extract(locals(), {'a': 'foo', 'b': 'bar'}
>>> a
'foo'
>>> b
'bar'

Nevertheless, I don't think these functions are "tremendously handy". Dynamic global/local variables are evil and error-prone -- PHP guys learned that when they discouraged register_globals. From my experience, few experienced PHP programmers or major frameworks use compact() or extract().

In Python, explicit is better than implicit:

a = 1
b = 2
# compact
c = dict(a=a, b=b)

# extract
a, b = d['a'], d['b']