Function creation at runtime in Python

Question

Is it possible to do something like this:

def fns(Names, Args, Bodies):
    for i in range(len(Names)):
        exec("def " + Names[i] + "(" + Args + "): " + Bodies[i])

All functions should be in the global scope, amount of calling code should not depend on number of functions.

I want to quickly create getters and setters for data structures made from lists. Specific fns() code doesn't matter much, it's about idea. — DSblizzard
– DSblizzard, Commented Apr 13, 2012 at 5:52
As others note, there is definitely a better way to do this. Creating global getters and setters for a data structure isn't the right choice in an OOC language anyway- just create a class. — David Robinson
– David Robinson, Commented Apr 13, 2012 at 6:17
There are several ways you could do this, but it depends on exactly what you're trying to acheive? Can you give a complete example, showing examples of Names, Args and Bodies? Off the top of my head, one way you could do this would be mess around with code objects, but there's probably a simpler and better way. — aquavitae
– aquavitae, Commented Apr 13, 2012 at 6:39

Joran Beasley · Accepted Answer · 2012-04-13 06:05:08Z

2

not a good idea.. however

for i in range(len(Names)):
    exec("def " + Names[i] + "(" + Args + "): " + Bodies[i]) #create locally
    globals()[Names[i]] = locals()[Names[i]]                           #assign to global space

but I wouldn't recommend doing this... and that's untested code

edited Apr 13, 2012 at 6:05

answered Apr 13, 2012 at 5:54

Joran Beasley

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6 Comments

jamylak Over a year ago

Do you mean uppercase names? Also you are assigning globals()[Names[i]] to a string i think.

DSblizzard Over a year ago

Yes: "TypeError: 'str' object is not callable"

jamylak Over a year ago

change it to globals()[Names[i]] = locals()[Names[i]]. Also I don't think you should be doing this as well, it is very hack-ish...

Joran Beasley Over a year ago

oops will fix now (should be locals()names[i]) ..... also I second @jamylak's opinion

Joran Beasley Over a year ago

make a generic function maybe or a subclass of list that has the getters and setters you want... theres not very many good reasons I can think of for dynamic code like what your talking about...

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