#100DaysOfCode in Python Transcripts
Chapter: Days 34-36: Refactoring / Pythonic code
Lecture: Refactoring 1: if-elif-else horror
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0:01
Alright, let's do this.
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Let's look at 10 ways to make your code
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more Pythonic.
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Let's start with these typical
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big if, elif, elif, elif,
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elif constructs.
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You must've seen code like this, right?
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You have the typical workout scheme.
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We check it Monday, elif Tuesday, Wednesday etc.
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And if it's not a day we raise the ValueError.
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Now this is pretty ugly
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but it's also not extensible
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in the sense that if want another
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maybe combination of Thursday and Friday
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to do something we have to add another elif.
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What if we change this in using a dictionary.
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So that we can just look up the key
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and return a value?
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I got this picture from the Code Complete Book
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which is an awesome read about code quality.
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So to refactor that,
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let's start with defining a workouts dictionary.
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And I'm just going to copy these in
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because it's quite some typing.
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Alright.
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And that gives us a workout scheme.
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And note that the dates are in random order
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because it's a dictionary.
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By the way there's another way
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to make this dictionary.
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And that is to use zip two sequences.
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So if I define a list of days
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and a list of routines,
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we can do something like
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workouts
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equals dict of a zip
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and a zip takes one or more sequences.
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So days, routines
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and here you can
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see we have an equal dict.
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Alright, now to go back
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to this refactoring example.
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Now with the dictionary in place
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you can see how much shorter
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and nicer this function looks.
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So note I can now just do a get
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on the dictionary.
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Looking up the day,
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and it gives me the routine
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or None, if today was not found.
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So we can explicitly check routine is None.
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And raise that ValueError,
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as we've seen before.
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And otherwise, just return the routine.
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Let's try it.
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Chest and biceps.
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What about
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Saturday rest
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and call it on nonsense.
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Yes I get a ValueError
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because nonsense is not a day.
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Alright, that's our first refactoring.
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And let's look at counting inside a loop next.
