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Groups > comp.lang.python > #82305

Re: When do default parameters get their values set?

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On Tue, Dec 9, 2014, at 21:44, Rustom Mody wrote:
> Nice example -- thanks.
> Elaborates the why of this gotcha -- a def(inition) is imperative.
> From a semantic pov very clean.
> From an expectation pov always surprising.

Of course, I used a lambda for this. The equivalent without would be:

def f():
    def g(x={}):
        return x
    return g

Ultimately it's no different from when any non-immutable expression is
executed.

def f: return {'x': {}}
f()['x'] is f()['x'] # False
d = f()
d['x'] is d['x'] # True

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When do default parameters get their values set? "bSneddon" <bsneddon@1:249/999.remove-cdt-this> - 2014-12-09 11:32 -0500
  Re: When do default parameters get their values set? "Chris Angelico" <chris.angelico@1:249/999.remove-cdt-this> - 2014-12-09 11:32 -0500
  Re: When do default parameters get their values set? "Dave Angel" <dave.angel@1:249/999.remove-cdt-this> - 2014-12-09 11:32 -0500
    Re: When do default parameters get their values set? Duncan Booth <duncan.booth@invalid.invalid> - 2014-12-09 21:18 +0000
      Re: When do default parameters get their values set? random832@fastmail.us - 2014-12-09 18:07 -0500
        Re: When do default parameters get their values set? Rustom Mody <rustompmody@gmail.com> - 2014-12-09 18:44 -0800
          Re: When do default parameters get their values set? random832@fastmail.us - 2014-12-10 13:38 -0500
            Re: When do default parameters get their values set? Rustom Mody <rustompmody@gmail.com> - 2014-12-10 18:18 -0800
              Re: When do default parameters get their values set? Chris Angelico <rosuav@gmail.com> - 2014-12-11 13:24 +1100
                Re: When do default parameters get their values set? Rustom Mody <rustompmody@gmail.com> - 2014-12-10 18:50 -0800
              Re: When do default parameters get their values set? Steven D'Aprano <steve@pearwood.info> - 2014-12-11 03:15 +0000
                Re: When do default parameters get their values set? Rustom Mody <rustompmody@gmail.com> - 2014-12-10 19:26 -0800
                Re: When do default parameters get their values set? Ben Finney <ben+python@benfinney.id.au> - 2014-12-11 14:49 +1100
                Re: When do default parameters get their values set? Chris Kaynor <ckaynor@zindagigames.com> - 2014-12-11 09:10 -0800
                Re: When do default parameters get their values set? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-12-12 09:51 +1100
              Re: When do default parameters get their values set? random832@fastmail.us - 2014-12-11 15:44 -0500
  Re: When do default parameters get their values set? "Tim Chase" <tim.chase@1:249/999.remove-cdt-this> - 2014-12-09 11:32 -0500

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