Question

I know this must be a trivial question, but I’ve tried many different ways, and searched quie a bit for a solution, but how do I create and reference subfunctions in the current module?

For example, I am writing a program to parse through a text file, and for each of the 300 different names in it, I want to assign to a category.

There are 300 of these, and I have a list of these structured to create a dict, so of the form lookup[key]=value (bonus question; any more efficient or sensible way to do this than a massive dict?).

I would like to keep all of this in the same module, but with the functions (dict initialisation, etc) at the
end of the file, so I dont have to scroll down 300 lines to see the code, i.e. as laid out as in the example below.

When I run it as below, I get the error ‘initlookups is not defined’. When I structure is so that it is initialisation, then function definition, then function use, no problem.

I’m sure there must be an obvious way to initialise the functions and associated dict without keeping the code inline, but have tried quite a few so far without success. I can put it in an external module and import this, but would prefer not to for simplicity.

What should I be doing in terms of module structure? Is there any better way than using a dict to store this lookup table (It is 300 unique text keys mapping on to approx 10 categories?

Thanks,

Brendan

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import ..... (initialisation code,etc )

initLookups()          # **Should create the dict - How should this be referenced?**
print getlookup(KEY)   # **How should this be referenced?**


def initLookups():
    global lookup
    lookup={}
    lookup["A"]="AA"
    lookup["B"]="BB"
    (etc etc etc....)


def getlookup(value)
    if name in lookup.keys():
        getlookup=lookup[name]
    else:
        getlookup=""

    return getlookup

Answer 1

A function needs to be defined before it can be called. If you want to have the code that needs to be executed at the top of the file, just define a main function and call it from the bottom:

import sys

def main(args):
    pass

# All your other function definitions here

if __name__ == '__main__':
    exit(main(sys.argv[1:]))

This way, whatever you reference in main will have been parsed and is hence known already. The reason for testing __name__ is that in this way the main method will only be run when the script is executed directly, not when it is imported by another file.

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Side note: a dict with 300 keys is by no means massive, but you may want to either move the code that fills the dict to a separate module, or (perhaps more fancy) store the key/value pairs in a format like JSON and load it when the program starts.