How to iterate over function arguments

locals() may be your friend here if you call it first thing in your function.

Example 1:

>>> def fun(a, b, c):
...     d = locals()
...     e = d
...     print e
...     print locals()
... 
>>> fun(1, 2, 3)
{'a': 1, 'c': 3, 'b': 2}
{'a': 1, 'c': 3, 'b': 2, 'e': {...}, 'd': {...}}

Example 2:

>>> def nones(a, b, c, d):
...     arguments = locals()
...     print 'The following arguments are not None: ', ', '.join(k for k, v in arguments.items() if v is not None)
... 
>>> nones("Something", None, 'N', False)
The following arguments are not None:  a, c, d

Answer:

>>> def foo(a, b, c):
...     return ''.join(v for v in locals().values() if v is not None)
... 
>>> foo('Cleese', 'Palin', None)
'CleesePalin'

Update:

'Example 1' highlights that we may have some extra work to do if the order of your arguments is important as the dict returned by locals() (or vars()) is unordered. The function above also doesn't deal with numbers very gracefully. So here are a couple of refinements:

>>> def foo(a, b, c):
...     arguments = locals()
...     return ''.join(str(arguments[k]) for k in sorted(arguments.keys()) if arguments[k] is not None)
... 
>>> foo(None, 'Antioch', 3)
'Antioch3'

def func(*args):
    ' '.join(i if i is not None else '' for i in args)

if you're joining on an empty string, you could just do ''.join(i for i in args if i is not None)

You can use the inspect module and define a function like that:

import inspect
def f(a,b,c):
    argspec=inspect.getargvalues(inspect.currentframe())
    return argspec
f(1,2,3)
ArgInfo(args=['a', 'b', 'c'], varargs=None, keywords=None, locals={'a': 1, 'c': 3, 'b': 2})

in argspec there are all the info you need to perform any operation with argument passed.

To concatenate the string is sufficient to use the arg info received:

def f(a,b,c):
    argspec=inspect.getargvalues(inspect.currentframe())
    return ''.join(argspec.locals[arg] for arg in argspec.args)

For reference: http://docs.python.org/library/inspect.html#inspect.getargvalues

Is this perhaps what you'd like?

def foo(a, b, c):
    "SilentGhost suggested the join"
    ' '.join(i if i is not None else '' for i in vars().values())

def bar(a,b,c): 
    "A very usefull method!"
    print vars()
    print vars().values()

Notice the use of vars(), which returns a dict.

How to iterate over function arguments

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