[Tutor] dynamic argument lists

[eShopping]

Hi

I have a GUI program that extracts some information from the user as 
strings, and I then want to use the strings to form an argument list 
to another function.  Hopefully the following code gives some flavour:

def myfunc(**kwargs):
     while kwargs:
         name, value = kwargs.popitem()
         print name, value

myfunc(a=1, b=2, c=3, d=4)
arg_str = "a=1, b=2, c=3, d=4"
myfunc(arg_str)

ARG_STR will be built up from the data extracted from the GUI.  I get 
this error

TypeError: myfunc() takes exactly 0 arguments (1 given)

I understand that ARG_STR is a string and that MYFUNC is expecting 
something else ,,, but not sure what it is.  I have tried various 
dictionary configurations such as

arg1 = ["a","b","c","d"]
arg2 = [1,2,3,4]
arg3 = dict(zip(arg1,arg2))
myfunc(arg3)

but still get the same error message.  All suggestions welcome!

Thanks in advance

Alun Griffiths