Detupleize a tuple for argument list

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  • Marco Wahl
    #1

    Detupleize a tuple for argument list

    Hi,

    I want to give a tuple to a function where the function
    expects the respective tuple-size number of arguments.

    The following session illustrates what I want to do and
    the respective failure.

    Python 2.4.1 (#7, Aug 3 2005, 14:55:58)
    [GCC 3.3.1 (SuSE Linux)] on linux2
    Type "help", "copyright" , "credits" or "license" for more information.
    >>def foo(a, b): print a, b
    ...
    >>t = (1, 2)
    >>def foo(a, b): print 'a == %s, b == %s' % (str(a), str(b))
    ...
    >>foo(1, 2)
    a == 1, b == 2
    >>foo(t)
    Traceback (most recent call last):
    File "<stdin>", line 1, in ?
    TypeError: foo() takes exactly 2 arguments (1 given)
    >>>
    One way to do what I want is--of course--to call
    foo(t[0], t[1]). My actual question is if there is a
    smarter way to do it.

    The situation for me is that I take the functions from
    a library that I cannot modify. On the other side in
    my code I use the tuples.


    Best wishes
    --
    Marco Wahl
    http://visenso.com


    Tags: None
    • Luke Plant
      #2
      Re: Detupleize a tuple for argument list

      Marco Wahl wrote:
      Hi,
      >
      I want to give a tuple to a function where the function
      expects the respective tuple-size number of arguments.
      ....
      One way to do what I want is--of course--to call
      foo(t[0], t[1]). My actual question is if there is a
      smarter way to do it.
      Yes, just this:

      foo(*t)

      Luke

        Comment

        • Steven D'Aprano
          #3
          Re: Detupleize a tuple for argument list

          On Wed, 05 Jul 2006 14:01:27 +0200, Marco Wahl wrote:
          Hi,
          >
          I want to give a tuple to a function where the function
          expects the respective tuple-size number of arguments.
          >
          The following session illustrates what I want to do and
          the respective failure.
          >
          Python 2.4.1 (#7, Aug 3 2005, 14:55:58)
          [GCC 3.3.1 (SuSE Linux)] on linux2
          Type "help", "copyright" , "credits" or "license" for more information.
          >>def foo(a, b): print a, b
          ...
          >>t = (1, 2)
          >>def foo(a, b): print 'a == %s, b == %s' % (str(a), str(b))
          ...
          >>foo(1, 2)
          a == 1, b == 2
          >>foo(t)
          Traceback (most recent call last):
          File "<stdin>", line 1, in ?
          TypeError: foo() takes exactly 2 arguments (1 given)
          Easy: foo(*t)

          --
          Steve.

            Comment

            • Marco Wahl
              #4
              Re: Detupleize a tuple for argument list

              Marco Wahl enlightened us with:
              >>foo(t)
              Traceback (most recent call last):
              File "<stdin>", line 1, in ?
              TypeError: foo() takes exactly 2 arguments (1 given)
              >
              Call foo(*t)
              Thank you very much Luke Plant, Steven D'Aprano and Sybren Stuvel.

              This was exactly what I was looking for. I'm happy now. ;-)
              --
              Marco Wahl
              http://visenso.com

                Comment

                • Bruno Desthuilliers
                  #5
                  Re: Detupleize a tuple for argument list

                  Marco Wahl wrote:
                  >>Marco Wahl enlightened us with:
                  >>
                  >>>>>>foo(t)
                  >>>
                  >>Traceback (most recent call last):
                  >> File "<stdin>", line 1, in ?
                  >>TypeError: foo() takes exactly 2 arguments (1 given)
                  >>
                  >>Call foo(*t)
                  >
                  >
                  Thank you very much Luke Plant, Steven D'Aprano and Sybren Stuvel.
                  >
                  This was exactly what I was looking for. I'm happy now. ;-)
                  FWIW, there's something similar for dicts and named args:
                  >>def foo(a, b): print str(a), str(b)
                  ....
                  >>kwargs = {'a' : 1, 'b': 2}
                  >>foo(**kwarg s)
                  1 2
                  >>>


                  --
                  bruno desthuilliers
                  python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for
                  p in 'onurb@xiludom. gro'.split('@')])"

                    Comment

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