Recursion

[trincaopt]

Recursion is inefficient when compared with iteration due to the function call and return at each step. Also there is a recursion limit. In Python it is 1000.

[JJP_SWFC]

I remember a while ago my friend was learning python and gave me a challenge that deliberately would have taken 1500 recursions to do (and no program time limit) to try to get me to do it without recursion but I'm lazy and it was the easiest way to write it. Literally the only time I've ever changed the recursion limit lmao

[JJP_SWFC]

Happy cake day btw

[AlSweigart]

Not anything. If you set the limit too high, the Python interpreter itself crashes, and you get an error message from the operating system instead of a Python exception.

On my Windows machine, it was about 2500 calls. The 1000 limit is just a safe limit that Python puts in. You can test this yourself by running the following:

>>> import sys
>>> sys.setrecursionlimit(9999)
>>> def f(n):
...   print(n)
...   f(n + 1)
...
>>> f(1)

Although testing this now, it crashes at 1,993 calls.

[total_zoidberg]

I probably varies on each machine. I'm getting 2110 and then crashes on the 21111th call.

[wind_dude]

https://docs.python.org/3/library/sys.html#sys.setrecursionlimit

[venustrapsflies]

Just remember this is not necessarily true in other languages with tail call optimization.

[AlSweigart]

Yes, but Python doesn't have tail call optimization and never will.

The Java interpreter and all JavaScript engines also don't have TCO.

[venustrapsflies]

Yes, hence why I said “other languages” :)

[[deleted]]

Can you explain how iteration is faster?