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Groups > comp.lang.python > #20206

Re: Postpone evaluation of argument

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Righard van Roy <pluijzer@gmail.com> writes:
> I want to add an item to a list, except if the evaluation of that item
> results in an exception.

This may be overkill and probably slow, but perhaps most in the spirit
that you're asking.

    from itertools import chain

    def r(x):
        if x > 3:
            raise(ValueError)
        return x

    def maybe(func):
      try:
         yield func()
      except:
         return

    def p(i): return maybe(lambda: r(i))

    your_list = list(chain(p(1), p(5)))
    print your_list

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Postpone evaluation of argument Righard van Roy <pluijzer@gmail.com> - 2012-02-11 00:01 +0100
  Re: Postpone evaluation of argument Paul Rubin <no.email@nospam.invalid> - 2012-02-10 15:57 -0800
    Re: Postpone evaluation of argument 88888 Dihedral <dihedral88888@googlemail.com> - 2012-02-11 03:16 -0800
  Re: Postpone evaluation of argument Jussi Piitulainen <jpiitula@ling.helsinki.fi> - 2012-02-11 10:54 +0200

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