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Date: Thu, 2 Feb 2012 17:24:23 -0800
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Subject: Re: multiple constructor __init__
From: Chris Rebert <clp2@rebertia.com>
To: Emmanuel Mayssat <emayssat@gmail.com>
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On Thu, Feb 2, 2012 at 5:09 PM, Emmanuel Mayssat <emayssat@gmail.com> wrote=
:
> Hello all,
>
> I would like to instantiate my class as follow
>
> QObject(<param1>, <parent>)
> QObject(<parent>)
>
> an example would be
> http://www.riverbankcomputing.co.uk/static/Docs/PyQt4/html/qmenu.html
>
> How can I do this without have to specify parent=3D<parent> in the second
> version
> (I always need to supply the parent parameter, but I would like to supply=
 it
> last)
>
> I have read this
> http://stackoverflow.com/questions/356718/how-to-handle-constructors-or-m=
ethods-with-a-different-set-or-type-of-argument
> but all the suggested methods do not work as I want
>
> Any idea?

I believe you can approximate that using a keyword-only argument
without a default value:

# Untested!
# Requires Python 3.x
class QObject(object):
    def __init__(self, param1=3Dsome_default, *, parent):
        # =E2=80=A6

obj1 =3D QObject(parent=3Ddaddy)
obj2 =3D QObject(arg1, parent=3Ddaddy)

obj3 =3D QObject(daddy) # ERROR
obj4 =3D QObject(arg1, daddy) # ERROR
obj5 =3D QObject() # ERROR

Cheers,
Chris
--
Using names instead of some arbitrary ordering makes much more sense.
http://rebertia.com