CODEWITHSUNDEEP
pythonpython-3.xfunction
Lara M.
Lara M.

Reputation: 855

Proper way to state a condition trough functions

I've got a code with different functions. Inside one of them there is a condition. I have to check if this condition occur to execute another function.

What's the proper way to do that? I've tried something like this but it doesn't work

Example:

class MyClass:
    def thisFunction(self):
        try: 
            "I'm doing things"
        except:
            self.stop = print("That's already done!")
    def thisOtherFunction(self):
        "I'm doing things with things done in thisFunction"
s = MyClass()
s.thisFunction()
if self.stop == None:
    s.thisOtherFunction()
else:
    pass

Thanks a lot!

Update

Actually it's a lot simplier doing:

class MyClass:
    def thisFunction(self):
        try: 
            "I'm doing things"
        except:
            self.stop = print("That's already done!")
   def thisOtherFunction(self):
        try:
            "I'm doing things with things done in thisFunction"
        except:
            pass
s = myClass()
s.thisFunction()
s.thisOtherFunction()

Thanks to Adam Smiths's example, I simply didn't think about that. Maybe it's not so much elegant, though.

Update2 Another way is to use def __init__ in this way:

    class MyClass:
        def __init__(self):
             self.commandStop = False
        def thisFunction(self):
            try: 
                "I'm doing things"
            except:
                self.commandStop = True
        def thisOtherFunction(self):
            "I'm doing things with things done in thisFunction"
        def conditionToGo(self):
             if self.commandStop == False:
                 print("That's already done!")
             else:
                 s.thisOtherFunction()
s = myClass()
s.thisFunction()
s.conditionToGo()

Upvotes: 0

Views: 48

Answers (1)

Adam Smith
Adam Smith

Reputation: 54173

I've made patterns before where I had to do a series of transforms to a value and it needs to pass a test each time. You could construct that with:

def pipeline(predicate, transformers):
    def wrapped(value):
        for transformer in transformers:
            value = transformer(value)
            if not predicate(value):
                raise ValueError(f"{value} no longer satisfies the specified predicate.") 
        return value
    return wrapped

Then, to construct an example, let's say I need to do some math on a number but ensure that the number never goes negative.

operations = [
    lambda x: x+3,
    lambda x: x-10,
    lambda x: x+1000,
    lambda x: x//2
]

job = pipeline(lambda x: x>0, operations)
job(3)  # fails because the sequence goes 3 -> 6 -> (-4) -> ...
job(8)  # is 500 because 8 -> 11 -> 1 -> 1001 -> 500

Upvotes: 1

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