[Python-list] if the else short form

Brendan Simon (eTRIX) brendan.simon at etrix.com.au
Wed Sep 29 14:23:31 CEST 2010


 On 29/09/10 9:20 PM, python-list-request at python.org wrote:
> Subject:
> if the else short form
> From:
> Tracubik <affdfsdfdsfsd at b.com>
> Date:
> 29 Sep 2010 10:42:37 GMT
>
> To:
> python-list at python.org
>
>
> Hi all,
> I'm studying PyGTK tutorial and i've found this strange form:
>
> button = gtk.Button(("False,", "True,")[fill==True])
>
> the label of button is True if fill==True, is False otherwise.
>
> i have googled for this form but i haven't found nothing, so can any of 
> you pass me any reference/link to this particular if/then/else form?
>

As others have pointed out, a tuple with two items is created and then
indexed by the integer conversion of conditional.  It is "creative"
coding but I wouldn't recommend using it either.

For this particular case you may achieve the same thing with:

    button = gtk.Button(str(fill==True))

or possibly just:

    button = gtk.Button(fill==True)

It's a little better but still not great.

A verbose form of something more generic may be:

    if fill:

        label = 'True'

    else:

        label = 'False'

    button = gtk.Button(label)

or possibly:

    label = 'True' if fill else 'False'
    button = gtk.Button(label)

or using a dict for label lookup:

    label = { True : 'True', False : 'False' }
    button = gtk.Button(label[fill])


Cheers, Brendan.

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