[Tutor] Passing functions(with parameters) as paramiters to (looping)functions.
ramit.prasad at jpmorgan.com
Tue Aug 16 19:26:56 CEST 2011
>def loop(fn ):
> for i in range(5):
> fn( )
>def this_function(a=" i am not a string"):
> print( a )
>loop(this_function("I am a string") ) ## note the only change is here
>## With this as output:
>I am a string
>Traceback (most recent call last):
> File "/home/jeff/MyPythonStuff/call_sub.py", line 9, in <module>
> loop(this_function("I am a string") )
> File "/home/jeff/MyPythonStuff/call_sub.py", line 4, in loop
> fn( )
>TypeError: 'NoneType' object is not callable
NOTE: All code is untested.
You get a NoneType because this_function returns a None. What is happening is the this_function("xxx") gets called first and then that return value gets passed into loop as 'loop(None)'. I am not sure exactly what you are trying to do, but I would probably do something like passing in a list of arguments.
def loop(fn, args):
for arg in args :
fn( arg )
The way I would get an argument gets passed to this_function is really dependent on your goal. You may want to look at itertools / map libraries as well for more options.
Ramit Prasad | JPMorgan Chase Investment Bank | Currencies Technology
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