Python stop execution of current indentation level

Question

Is there a way to stop the execution of the current indentation level? I'm looking for a way to break out of a block comparable to the break-statement in loops.

if some_state:
    if bool1:
        <jump to some-final-code> # Looking for this operator
    <some code>
    if bool2:
        <jump to some-final-code> # Looking for this operator
    <moa code>
elif some_other_state:
    <some_other_conditions_with_equally_possible_jumps>
<some_final_code>

I know that many ways exist to solve this in a readable way. Let's assume the code of the whole block is semantically related and should not be separated info different methods. Raising exceptions adds a lot of lines of code and another unwanted level of incomprehension.

Python does not have a goto command. [Is there a label/goto in Python?](https://stackoverflow.com/q/438844/3890632) — khelwood, Jul 23 '21 at 11:00
Also note that "stop the execution of the current indentation level" would not help you: you're trying to stop execution of the indentation level above the current indentation level. — khelwood, Jul 23 '21 at 11:05
@khelwood Being able to stop 1 indentation level implies the capability of stoping n-levels. Something like a goto statement would be perfect, but the docs refer to using exceptions instead. — MyNameIsFu, Jul 23 '21 at 11:13
"Being able to stop 1 indentation level implies the capability of stoping n-levels."—No it doesn't. "the docs refer to using exceptions"—You specifically ruled out using exceptions in your question, so I'm not sure what your point is there. — khelwood, Jul 23 '21 at 11:15
I'm looking for inspirations on 'how to produce readable code without bloating everything up with exceptions or nested conditions' — MyNameIsFu, Jul 23 '21 at 11:20

Kemp · Accepted Answer · 2021-07-23T14:02:33.340

You could always invert the conditions, which would have the same effect if you don't mind more indentation levels:

if some_state:
    if not bool1:
        <some code>
        if not bool2:
            <moa code>
elif some_other_state:
    <some_other_conditions_with_equally_possible_jumps>
<some_final_code>

Alternatively, exceptions don't add many lines of code at all:

class GotoCleanup(Exception):
    pass

... whatever other code you have ...

try:
    if some_state:
        if bool1:
            raise GotoCleanup
        <some code>
        if bool2:
            raise GotoCleanup
        <moa code>
    elif some_other_state:
        <some_other_conditions_with_equally_possible_jumps>
finally:
    <some_final_code>

If you want to make sure you only catch your specific exception then you have to add a couple of extra lines:

try:
    if some_state:
        if bool1:
            raise GotoCleanup
        <some code>
        if bool2:
            raise GotoCleanup
        <moa code>
    elif some_other_state:
        <some_other_conditions_with_equally_possible_jumps>
except GotoCleanup:
    pass
finally:
    <some_final_code>

This will allow other exceptions to propogate as usual and would be considered best practice rather than swallowing all exceptions.

I'm trying to avoid deep indentation levels. It's hard to keep track after more than 5 indentations which block started/continues/ends. Anyway a valid solution, thanks — MyNameIsFu, Jul 23 '21 at 11:09
I've updated to include an exceptions example. You mentioned bloat with that, but it basically just adds two lines to your example. — Kemp, Jul 23 '21 at 11:48
That alternative can actually become quite readable and powerful. Thanks very much :-) — MyNameIsFu, Jul 23 '21 at 12:12

score 0 · Answer 2 · answered Jul 23 '21 at 11:06

0

How about encapsulating the behavior into a function? Then you can use return to end the execution of that function.

def myFunction():
    if some_state:
        if bool1:
            return
        <some code>
        if bool2:
            return
        <moa code>
    elif some_other_state:
        <some_other_conditions_with_equally_possible_jumps>

myFunction()
<some_final_code>

answered Jul 23 '21 at 11:06

Taxel

3,859
1
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That's what i'm currently doing, but i was wondering whether there might be a way to not split the logic across different methods. Still Thanks! – MyNameIsFu Jul 23 '21 at 11:11

Python stop execution of current indentation level

2 Answers2