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Re: 'complex' function with string argument.

References <8c862bec-815e-424c-81e2-8f37ebab1c35@googlegroups.com> <lg779d$5f4$2@speranza.aioe.org> <mailman.8201.1395075805.18130.python-list@python.org> <87y508r8ro.fsf@elektro.pacujo.net>
Date 2014-03-18 05:59 +1100
Subject Re: 'complex' function with string argument.
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.8218.1395082794.18130.python-list@python.org> (permalink)

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On Tue, Mar 18, 2014 at 5:15 AM, Marko Rauhamaa <marko@pacujo.net> wrote:
>>> This  '3 + 2j'  is not a number, its an algebraic sum.
>>>
>>> This '3+2j' is a complex number. Ok, maybe not, but its closer to what
>>> we expect (I'm sorry, but I like i instead of j )
>>
>>Hmm. That's a pretty tricky distinction.
>
> Is "-2.0" a literal?
>
> What's the outcome of
>
>    -2.0.__str__()

If you mean (-2.0).__str__(), then it returns '-2.0', but that proves
nothing. Lots of objects have a str() which isn't a literal. Closer to
what you're talking about would be repr(), but even then, it doesn't
prove that something's a literal. The easiest way to tell is probably
ast.parse():

>>> ast.dump(ast.parse("-2.0"))
'Module(body=[Expr(value=UnaryOp(op=USub(), operand=Num(n=2.0)))])'

It's an expression consisting of unary minus and the float literal 2.0.

ChrisA

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Thread

'complex' function with string argument. Jayanth Koushik <jnkoushik@gmail.com> - 2014-03-15 09:26 -0700
  Re: 'complex' function with string argument. Mark H Harris <harrismh777@gmail.com> - 2014-03-17 11:18 -0500
    Re: 'complex' function with string argument. Chris Angelico <rosuav@gmail.com> - 2014-03-18 04:03 +1100
      Re: 'complex' function with string argument. Marko Rauhamaa <marko@pacujo.net> - 2014-03-17 20:15 +0200
        Re: 'complex' function with string argument. Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-17 12:28 -0600
        Re: 'complex' function with string argument. Chris Angelico <rosuav@gmail.com> - 2014-03-18 05:59 +1100
          Re: 'complex' function with string argument. Marko Rauhamaa <marko@pacujo.net> - 2014-03-17 21:22 +0200
            Re: 'complex' function with string argument. Chris Angelico <rosuav@gmail.com> - 2014-03-18 06:32 +1100
            Re: 'complex' function with string argument. Steven D'Aprano <steve@pearwood.info> - 2014-03-18 04:08 +0000
      Re: 'complex' function with string argument. Mark H Harris <harrismh777@gmail.com> - 2014-03-17 13:20 -0500
    Re: 'complex' function with string argument. Steven D'Aprano <steve@pearwood.info> - 2014-03-18 04:52 +0000
      Re: 'complex' function with string argument. Chris Angelico <rosuav@gmail.com> - 2014-03-18 15:59 +1100
      Re: 'complex' function with string argument. Mark H Harris <harrismh777@gmail.com> - 2014-03-18 11:14 -0500
        Re: 'complex' function with string argument. wxjmfauth@gmail.com - 2014-03-19 00:30 -0700
          Re: 'complex' function with string argument. Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 10:51 +0200
            Re: 'complex' function with string argument. wxjmfauth@gmail.com - 2014-03-19 02:52 -0700
              Re: 'complex' function with string argument. Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 12:09 +0200
                Re: 'complex' function with string argument. Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-19 04:33 -0600
                Re: 'complex' function with string argument. Marko Rauhamaa <marko@pacujo.net> - 2014-03-19 12:53 +0200
                Re: 'complex' function with string argument. Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-19 13:35 -0600
                Re: 'complex' function with string argument. Skip Montanaro <skip@pobox.com> - 2014-03-19 06:04 -0500
                Re: 'complex' function with string argument. wxjmfauth@gmail.com - 2014-03-19 07:35 -0700
                Re: 'complex' function with string argument. Ian Kelly <ian.g.kelly@gmail.com> - 2014-03-19 12:45 -0600
  Re: 'complex' function with string argument. Mark Dickinson <mdickinson@enthought.com> - 2014-03-17 17:55 +0000
  Re: 'complex' function with string argument. Terry Reedy <tjreedy@udel.edu> - 2014-03-17 18:06 -0400
  Re: 'complex' function with string argument. Skip Montanaro <skip@pobox.com> - 2014-03-17 18:59 -0500
  Re: 'complex' function with string argument. Chris Angelico <rosuav@gmail.com> - 2014-03-18 11:16 +1100
  Re: 'complex' function with string argument. Skip Montanaro <skip@pobox.com> - 2014-03-17 20:07 -0500
  Re: 'complex' function with string argument. Christian Gollwitzer <auriocus@gmx.de> - 2014-03-18 08:04 +0100
    Re: 'complex' function with string argument. Chris Angelico <rosuav@gmail.com> - 2014-03-18 18:11 +1100
    Re: 'complex' function with string argument. Steven D'Aprano <steve@pearwood.info> - 2014-03-18 08:00 +0000
      Re: 'complex' function with string argument. Christian Gollwitzer <auriocus@gmx.de> - 2014-03-18 09:21 +0100
        Re: 'complex' function with string argument. Marko Rauhamaa <marko@pacujo.net> - 2014-03-18 16:00 +0200

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