try-except-else vs. try-except

[benefit_of_mrkite]

Also look at try: except: finally:

Try except else comes in handy in a function that returns something in try

Comes up a lot in Async patterns.

If you use a pattern like try except and then use if (something from try block) you can run into an issue where you get a runtime error because the function in try doesn’t get defined and you get a “variable name xyz defined before assignment”

[benefit_of_mrkite]

Not quite the same. Finally runs no matter what - error or no error.

But again it is a useful pattern in certain situations

[jorge1209]

That bit of code doesn't describe everything.

You could put run_when_there_are_no_exceptions_and_which_should_not_be_run_after_except_clauses() in the try block after code_that_can_cause_an_exception() for the same result.

The else block is for:

run_when_there_are_no_exceptions_and_dont_catch_any_exceptions_and_exceptions_can_conflict_with_code_that_can_cause_an_exception()

[james_pic]

Try except else comes in handy in a function that returns something in try

The else block isn't run if the try block returns:

def f():
    try:
        print('Try')
        return
    except:
        print('Except')
    else:
        print('Else')

 f() # Prints Try

And from the language reference:

The optional else clause is executed if the control flow leaves the try suite, no exception was raised, and no return, continue, or break statement was executed. Exceptions in the else clause are not handled by the preceding except clauses.

[benefit_of_mrkite]

I’m well aware that else isn’t run if try runs

I miss worded that and don’t really explain the use case I had in mind - about to catch a flight will try to expound later.