return in a function

[Skaperen]

suppose i have a bunch of code like

if first_name == 'alex':
    return 1
if middle_name == 'larry':
    return 2
if middle_name == 'mark':
    return 3
if first_name == 'sarah':
    return 4
if surname == 'smith':
    return 5

duplicated in several places and i want to reduce the duplication by putting it in a function. how would i do that?

[michael1789]

Python dictionary.

dict = {'alex' : 1,
        'larry' : 2, 
        'mark' : 3}

print(dict['mark'])

[snippsat]

Dictionary as mention bye michael1789,but don't use dict as Python use that name.
Can throw in in get to handle missing key,and give a familiar name of what is called other languages.

def switch_case(record, search):
    return record.get(search, f'<{search}> not in record')

if __name__ == '__main__':
    record = {
        'alex': 1,
        'larry': 2,
        'mark': 3
        }
    search = 'mark'
    print(switch_case(record, search))

Need or not,so to we get switch case version in Python 3.10.
Called Structural Pattern Matching which is more powerful that just simple switch case.

[ndc85430]

Nice. I didn't realise 3.10 had pattern matching.

[Skaperen]

Python dictionary.

dict = {'alex' : 1,
        'larry' : 2, 
        'mark' : 3}

print(dict['mark'])

the example i gave involves testing various different variables. maybe it's a bad example. the "bunch of code" can't be changed. the question is about how to have function A call function B and have function B effect the return all the way to the caller of function A. put the "bunch of code" inside function B so function A can just call function B in all those places it had that "bunch of code". but what about those returns? can function B do a return for function A? not really. see the complication?

[Gribouillis]

Function A could just call

def A():
    ...
    return B()

[Skaperen]

what if the "bunch of code" only returns in some cases and "falls through" in others?

[Gribouillis]

You could do like list.index()

def A():
    try:
        return B(value)
    except ValueError:
        pass

[Skaperen]

so do i get to put the duplicated and complicated decision making code in a function? i'm guessing B() should raise an exception. then A() gets the exception or A()'s caller does.

[nilamo]

I would use a sentinel value (None, if that's not valid) to mark a Not Found case. So for this:

def lookup(first_name, middle_name, surname):
    if first_name == 'alex':
        return 1
    if middle_name == 'larry':
        return 2
    if middle_name == 'mark':
        return 3
    if first_name == 'sarah':
        return 4
    if surname == 'smith':
        return 5
    return None

if (res := lookup(f, m, s)) is None:
    # not found