#100DaysOfCode in Python Transcripts
Chapter: Days 34-36: Refactoring / Pythonic code
Lecture: Refactoring 9: be explicit in your exceptions
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One thing that the Zen is saying is explicit is
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better than implicit and I want to show you
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that concept with a couple of examples here.
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For example, if you do a from module import *,
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it imports everything in your namespace if this would
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import full or bar and you define such a variable or
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function that will override it
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and that leads to very obscure box.
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So don't do import *.
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Make it explicit what you're importing.
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So from module import full, bar.
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Another coding horror is something like
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try and except pass.
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Now this is like the black hole or monster that
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absorbs all possible errors, muting them away
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and you won't see anything in return.
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So whatever happens, even if I were to interrupt
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the program with a control C which would raise
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the keyboard interrupt exception,
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that will be silenced as well so I cannot even
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kill my program basically.
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So don't do this.
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No bare exceptions, make it explicit.
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So a little bit better will be for example,
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at least I get some information,
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or let's divide it by 0, I'm still shouting
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and I get another error.
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And you see these operations lead to different exceptions
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so the best way to do it is
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to explicitly name the exceptions.
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Again, try to divide number one by number two
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and let's go through the different exceptions we might get.
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Here for example, if I get a ZeroDivision error,
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I just return 0.
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That's my handling of the exception.
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If I get a type error,
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and here I just print a message but I don't
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really have a way to allow this
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and so I just reraise the exception.
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And if something else goes wrong you still can instead of
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doing accept pass or accept print something you can at least
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say accept exception as variable and browse that variable.
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And you can send this to a log file for example.
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To have at least a little bit more information
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when you're debugging the problem.
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So now it's from the cell and call it with a string.
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And here you see that it entered the type error
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and I get the message related to type error
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and it reraised the exception and if I divide by 0,
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here we don't have to crash anymore because I explicitly
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handled ZeroDivision error.
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Printed the message and return 0.
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Great, and that concludes number 9.
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Explicit is better than implicit.
