list assignment

[Norvell Spearman]

In "Learning Python," by Lutz and Ascher, there's a table showing different
assignment statement forms. One form shown is list assignment. The authors
give this as an example:

[spam, ham] = ['yum', 'YUM']

I don't see how this is any different than a tuple unpacking assignment:
[color=blue][color=green][color=darkred]
>>> a, b = 1, 2
>>> a, b[/color][/color][/color]
(1, 2)[color=blue][color=green][color=darkred]
>>> [a, b] = [1, 2]
>>> a, b[/color][/color][/color]
(1, 2)

In both instances the names a and b are both mapped to 1 and 2 so why are there
two different forms?

Thanks for any answers.

--
Norvell Spearman

[Raymond Hettinger]

Re: list assignment

> [spam, ham] = ['yum', 'YUM'][color=blue]
>
> I don't see how this is any different than a tuple unpacking assignment:
>[color=green][color=darkred]
> >>> a, b = 1, 2[/color][/color][/color]

It's not different. They are ways of writing the same thing.


Raymond Hettinger

[Jeffrey Schwab]

Re: list assignment

Raymond Hettinger wrote:[color=blue][color=green]
>> [spam, ham] = ['yum', 'YUM']
>>
>>I don't see how this is any different than a tuple unpacking assignment:
>>[color=darkred]
>> >>> a, b = 1, 2[/color][/color]
>
>
> It's not different. They are ways of writing the same thing.[/color]

TMTOWTDI, after all. :)

[Norvell Spearman]

Re: list assignment

Raymond Hettinger wrote:[color=blue]
> It's not different. They are ways of writing the same thing.[/color]

Lutz and Ascher have tuple and list assignment as separate entries in their
assignment statement forms table so I was expecting there to be some
difference; thanks for setting me straight.

--
Norvell Spearman

[Norvell Spearman]

Re: list assignment

Jeffrey Schwab wrote:[color=blue]
> TMTOWTDI, after all. :)[/color]

A bit ironic that that's the official motto of Perl, don't you think?

--
Norvell Spearman

[Bernhard Herzog]

Re: list assignment

Norvell Spearman <norvell@stenoc all.com> writes:
[color=blue]
> Lutz and Ascher have tuple and list assignment as separate entries in
> their assignment statement forms table so I was expecting there to be
> some difference; thanks for setting me straight.[/color]

In older Python versions there was a difference between list unpacking
and tuple unpacking. The former would only work with lists and the
latter with tuples. With Python 1.5, both were unified into a more
general sequence unpacking, but for backwards compatibility both
syntaxes were kept.

Bernhard

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