Are you allowed to modify func_defaults (defaults in Python 3.x) in Python?

Asked Dec 09 '12 at 05:09

Active Dec 09 '12 at 05:16

Viewed 2,544 times

9

I've tried doing this in Python 2.6, and it does "work":

>>> def f(i='I'): return i
...
>>> f.func_defaults = (10,)
>>> f()
10

But is this officially specified behavior, or am I hitting an implementation-specific behavior?

asked Dec 09 '12 at 05:09

allyourcode

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3

Just because it works doesn't mean you should actually *do* it! – Ned Batchelder Dec 09 '12 at 05:35

1 Answers1

13

In the documentation func_defaults is documented as "writable", so it would seem to be defined behavior.

answered Dec 09 '12 at 05:16

BrenBarn

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Awesome! Docs also say this is new as of 2.4. – allyourcode Dec 09 '12 at 05:21
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This seems to be respected in practice too: it works in IronPython 3.0.0, Jython 2.5.1+, and pypy-1.9.1. – DSM Dec 09 '12 at 05:28
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@allyourcode: What's new in 2.4 is `func_name` being writable, not `func_defaults`. – BrenBarn Dec 09 '12 at 05:30