Recursive calls without using function's name

Question

As you can see in the code below, recursive calls using function's name fail if the original function is deleted.

Is there any means to reference the function in its own body by something like this or self?

>>> def count_down(cur_count):
...     print(cur_count)
...     cur_count -= 1
...     if cur_count > 0:
...         count_down(cur_count)
...     else:
...         print('Ignition!')
...     
>>> count_down(3)
3
2
1
Ignition!
>>> zaehle_runter = count_down
>>> zaehle_runter(2)
2
1
Ignition!
>>> del count_down
>>> zaehle_runter(2)
2
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "<input>", line 5, in count_down
NameError: name 'count_down' is not defined

Can you think of anything that can be referenced in such a way once it has been deleted? — Scott Hunter
– Scott Hunter, Commented Nov 8, 2019 at 20:39

Jean-François Fabre · Accepted Answer · 2019-11-08 20:44:13Z

3

When you call your function recursively, the function name is searched in the (global) scope.

Since the name is now deleted, it cannot be found.

To workaround this, you can create an internal function that does the recursive job. That makes your recursive function not affected by this deletion, since it's no longer recursive, but just calls an internal recursive function

def count_down(cur_count):
    def internal_count_down(cur_count):
       cur_count -= 1
       if cur_count > 0:
           internal_count_down(cur_count)
       else:
           print('Ignition!')
    internal_count_down(cur_count)

answered Nov 8, 2019 at 20:44

Jean-François Fabre♦

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1 Comment

Min-Soo Pipefeet Over a year ago

It's not exactly an answer to my question - so I assume the answer is 'no' - , but still the best workaround I can think of. Therefore: accepted. :-)

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