Calling a function with unknown arguments?

[Rob]

I can get a list of a function's arguments.

>>def bob(a, b):

.... return a+b
....

>>bob.func_code .co_varnames

('a', 'b')

Let's say that I also have a dictionary of possible arguments for this
function.

>>possible = {'a':10, 'b':5, 'c':-3}

How do I proceed to call bob(a=10, b=5) with this information?

Thanks!

[Grant Edwards]

Re: Calling a function with unknown arguments?

On 2007-03-07, Rob <crowell@mit.ed uwrote:

I can get a list of a function's arguments.

>>>def bob(a, b):

... return a+b
...

>>>bob.func_cod e.co_varnames

('a', 'b')
>
Let's say that I also have a dictionary of possible arguments for this
function.

>>>possible = {'a':10, 'b':5, 'c':-3}

>
How do I proceed to call bob(a=10, b=5) with this information?

bob(a=possible['a'],b=possible['b'])

--
Grant Edwards grante Yow! BRILL CREAM is
at CREAM O' WHEAT in another
visi.com DIMENSION...

[Gabriel Genellina]

Re: Calling a function with unknown arguments?

En Wed, 07 Mar 2007 19:55:08 -0300, Rob <crowell@mit.ed uescribió:

I can get a list of a function's arguments.

>>>def bob(a, b):

... return a+b
...

>>>bob.func_cod e.co_varnames

('a', 'b')
>
Let's say that I also have a dictionary of possible arguments for this
function.

>>>possible = {'a':10, 'b':5, 'c':-3}

>
How do I proceed to call bob(a=10, b=5) with this information?

You're almost done. Notice that co_varnames includes local variables too;
only the first co_argcount are positional arguments.
If you only want to deal with positional arguments (no *args, no **kw):

pydef bob(a,b):
.... c = a+b
.... return c
....
pybob.func_code .co_varnames
('a', 'b', 'c')
pybob.func_code .co_argcount
2
pyargs = dict((name, possible[name]) for name in
bob.func_code.c o_varnames[:bo
b.func_code.co_ argcount] if name in possible)
pyargs
{'a': 10, 'b': 5}
pybob(**args)
15

It can handle missing arguments (if they have a default value, of course):

pydef bob(a, k=3):
.... return a+k
....
pyargs = dict((name, possible[name]) for name in
bob.func_code.c o_varnames[:bo
b.func_code.co_ argcount] if name in possible)
pyargs
{'a': 10}
pybob(**args)
13

--
Gabriel Genellina

[Tombo]

Re: Calling a function with unknown arguments?

On Mar 7, 10:55 pm, "Rob" <crow...@mit.ed uwrote:

I can get a list of a function's arguments.>>def bob(a, b):
>
... return a+b
...>>bob.func_c ode.co_varnames
>
('a', 'b')
>
Let's say that I also have a dictionary of possible arguments for this
function.
>

>possible = {'a':10, 'b':5, 'c':-3}

>
How do I proceed to call bob(a=10, b=5) with this information?
>
Thanks!

You can do this with a list comprehension:
bob(*[possible[k] for k in bob2.func_code. co_varnames])

The LC creates a list of arg values in the same order as the var names
for the function. Putting a * before the list when you call bob()
turns that list into it's arguments.


Alternativly (and this may not be useful) you can call a function with
a dictionary of arguments:

def bob(**kwargs):
print kwargs

possible = {'a' : 10, 'b':5, 'c':-3}

>>bob(**possibl e)

{'a': 10, 'c': -3, 'b': 5}

>>>

Tom

[Rob]

Re: Calling a function with unknown arguments?

You can do this with a list comprehension:

bob(*[possible[k] for k in bob2.func_code. co_varnames])
>
The LC creates a list of arg values in the same order as the var names
for the function. Putting a * before the list when you call bob()
turns that list into it's arguments.

Thanks Tom! This turns out to be exactly what I needed.