CODEWITHSUNDEEP
pythonvariablesmodulepython-3.xglobal
gnr
gnr

Reputation: 2414

Python's use of global vs specifying the module

Was wondering if anyone had any thoughts on the use of Python's global vs. referencing the module itself. While in the past I used global when needed, I've found it somewhat clearer to do the second method (and recently have tended to favor this syntax):

import sys
mod = sys.modules[__name__]

counter = 0

def incrementGlobal():
    global counter
    counter += 1

def incrementMod():
    mod.counter += 1

Obviously both of them work fine, but if anyone has any strong opinions (what is more pythonic, performance etc), I'd love to hear them.

Btw I end up using either of these in situations where the module naturally encapsulates all the methods and attributes of what would be a single class, and rather than reference incrementmodule.IncrementClass.counter i can just use incrementmodule.counter.

Upvotes: 5

Views: 497

Answers (2)

Ethan Furman
Ethan Furman

Reputation: 69021

  • Performance: using the global style will be ever so slightly faster, as it only needs one name lookup instead of two (would only matter in a tight loop of many many thousands).

  • Style: the mod.xxx style mirrors the way you would access globals from another module that you had imported:

`

import foo
foo.eggs = 'scrambled'

The global method is more common, but your mod.xxx method is also easy to understand and very readable.

Upvotes: 3

dhwthompson
dhwthompson

Reputation: 2519

Go with global every time. The global keyword is an obvious and readily recognisable pattern for modifying something at module level. Giving a module a reference to itself from sys.modules seems a needlessly convoluted way of going around it, and is likely to confuse the next programmer who looks at it.

Upvotes: 5

Related Questions