how to exit exec() like in a function in Python

Question

I’m currently trying to make an self-modifying algorithm in Python.

To do that, i have a string containing an algorithm that i run using the exec(algorithm) function inside another funciton.

the algorithm that i want to run looks like this :

   if (a):
       do_something()
       return
   if (b):
       do_something_else()
       return
   ...

the problem is that "exec()" does not act like a function and so the "return" won’t work as such.

Of course, it works when i modify the algorithm string into :

def function ():

  if (a):
        do_something()
        return
  if (b):
        do_something_else()
        return
    ...

function()

But what i want is the keyword that replace "return" in exec().
The keyword that only exits the exec() (not the whole program), if it exists

Asked By: Marcocorico

||

Source

Answer 1

You can use the sys.exit() function to exit from within the exec() function without terminating the entire program. You just need to catch the SystemExit exception that sys.exit() raises and handle it appropriately.

import sys

def run_algorithm(algorithm):
try:
exec(algorithm)
except SystemExit:
pass

algorithm = ”’
if a:
print("a is true")
sys.exit()
if b:
print("b is true")
sys.exit()
”’

run_algorithm(algorithm)

Answered By: yunusdjanov

how to exit exec() like in a function in Python

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