Detupleize a tuple for argument list

[Marco Wahl]

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

[Luke Plant]

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

[Steven D'Aprano]

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.

[Marco Wahl]

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

[Bruno Desthuilliers]

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(**kwargs)

1 2

>>>

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