Call a function dynamically from a variable - Python

Question

Ok so I have two files, filename1.py and filename2.py and they both have a function with same name funB. The third file process.py has function that calls function from either files. I seem to be struggling in calling the correct function.

In process.py:

from directoryA.filename1 import funB
from directoryA.filename2 import funB
def funA:
 #do stuff to determine which filename and save it in variable named 'd'
 d = 'filename2'
 # here i want to call funB with *args based on what 'd' is 

So i have tried eval() like so:

 call_right_funB = eval(d.funB(*args)) 

but it seems not to work.

Any help is appreciated.

• Jon Clements: Can't you just from directoryA.filename1 import funB as f1 in this case? Or do you really need to dynamically lookup the module?
• Darth: @JonClements Thanks, Yes I need to dynamically look up the module
• Antti Haapala: They're not "directory.filename" but "package.module" or am I missing something?
• Darth: @AnttiHaapala its 'package.module' I used 'directory.filename' for simplifying and clarification purpose only

Answer 1

The problem is, you can't use eval() with a combination of a string and a method like that. What you have written is:

call_right_funB = eval('filename'.funB(*args))

What you can do is:

call_right_funB = eval(d + '.funB(*args)')

But this is not very pythonic approach. I would recommend creating a dictionary switch. Even though you have to import entire module:

import directoryA.filename1
import directoryA.filename2
dic_switch = {1: directoryA.filename1, 2: directoryA.filename2}
switch_variable = 1
call_right_funB = dic_switch[switch_variable].funB(*args)

Hope it helps.

• Darth: Thank you, the first "unpythonic" way works fine. With Dictionary switch how would i call then function 'funB'
• mdpt: You are welcome :-) call_right_funB = dict_switch[switch_variable].funB(*args) should work fine. Edit: If you are using it only once, you can also do: call_right_funB = {1: filename1, 2: filename2}[switch_variable].funB(*args)
• Darth: I get AttributeError: 'str' object has no attribute 'funB'
• mdpt: @darth haven't you write dictionary values as strings? Notice that in dict_switch they are saved as keywords, not as strings.
• Darth: It was string but if i save as keywords I get TypeError: 'module' object is not subscriptable