Modern Python Projects Transcripts
Chapter: Writing code
Lecture: Pylint
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0:00
So, I'm back to the original version of my ugly code, and I will try to install,
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Pylint and run it. So first we have to open the command palette and search
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for select linter, this one Python Select Linter and we want to select Pylint
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As you can see, nothing really happened because we don't have Pylint installed. So, let's go and install it with pipx,
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Just like with black. Let's copy the path to the binary and let's add it to the settings, search for pylint path and copy it here.
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As you can see, I already did that in the past. It can also happen that when you select Pylint Linter,
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you will get a pop up here saying that Pylint is not installed. Do you want to install it?
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You can press okay and VSCode will download and install Pylint for you and that will also work that way.
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You don't have to modify any settings in the configuration file.
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I usually don't install packages directly through VSCode because that way I don't really
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know where VSCode, installs them. If I want to go and update those packages I usually can't find them later.
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So, I prefer to install packages first and then point VSCode to use them But feel free to just click okay in the pop up.
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when VSCode will set up everything for you. So, we have selected Pylint. Let's now enable Linting.
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So, we have Linting enabled and nothing really happened. So, let's see what's wrong. There are no problems.
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What if we actually run Pylint on this code in the terminal? Ah, Great. My code was rated at -5. Out of -10 out of 10.
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That's great score. So in the terminal we see a lot of warnings, but not in the VSCode. Let's see what's wrong. VSCode.
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Has this output tab with output from different extensions and different parts of VSCode
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So, usually you can do this to check if everything is working fine of or if there are some errors. I don't see any error about Pylint not being found
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So, let's just try to added one more time as a Linter. Okay, This time it worked. We can see more red underscores quickly errors.
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So, let's see what pylint is reporting, it correctly detected that we don't have non existing
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function in itertools. So let's remove that, undefined variable. So that's correct. Let's try to define this variable. unused
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variable here and here. No value for arguments, cell. So this already can point us into direction of what might be wrong.
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So with those two information, I can see like Okay, I forgot to pass me here. try again. No problems anymore.
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So, it didn't detect that it should be double underscore Main(__main__). But this is kind of tricky error to spot, if we fix it and we can
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run it working fine. So, as you can see with Pylint, we were able to spot a lot of errors before we run our code the first
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time. If you have used Pylint outside of VSCode, you might be surprised why Pylint is not complaining about some of the additional problems like
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missing white spaces or additional spaces here and there to show you what I mean. Let's run Pylint in the terminal again on this ugly2 file.
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That, according to VSCode, has no more problems. As you can see here. There are still some other problems
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that we have to fix, like missing docstrings in the module, in the class or in the function,
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too few public methods, missing functional method docstring and so on. That's because when you check the documentation of VSCode,
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you can see that VSCode has some default Pylint rules that are supposed to be friendly to the largest number of Python developers.
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The thing with Pylint is that it's quite strict. It complains about missing documentation about too few public methods,
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or even if you create a class without init method, it will still complain about that. So, it really tries to make you right perfect,
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well documented code. But sometimes you know better what you're doing. If you're writing a simple script that you are going to use once,
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then maybe you don't feel like documenting every function. On the other hand, if you want to enable all Pylint warnings,
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you can go to the VSCode documentation, and here you can see that there is pylintUseMinimalCheckers option that is currently
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set to true when we set it to false, then Pylint will by default, show us all the warnings. So, let's try that settings set for this guy.
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And now you can see we have all the warnings and use import, missing documentation and too few public methods, missing documentation.
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But for example, it's not complaining about additional white spaces here,
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so those are all the warnings, that we will see with the default Pylint settings.
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But Pylint has also some additional checkers that are disabled by default, but you can enable them. When you go to the Pylint documentation,
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technical reference and optional Pylint checkers, This option is quite well hidden documentation. So, I'll put a link in the resources Page.
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And here you can see some optional Pylint checkers that you can enable, to enable those
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additional checkers. You will need to create a .pylintrc file and add them under the load plugins parameter. Some of the checkers here are very useful.
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For example, there is one that will warn you when you use a Deprecated
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builtin function. So the function that will be soon removed from Python or there is another one that will complain when you use else-if
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instead of elif statement. So, those optional checkers can further help you when you write your code, on top of the plugins that come with pylint,
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there are also plug ins that you can install separated from Pypi. For example, if you are using a Web framework like Django,
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you can install a Pylint plugin called Pylint Django. It will suppress some warnings that don't apply to your Python code, when you're writing a
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Django website, and it will also add some new checks specific to Django code.
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Unfortunately, I haven't found like one repository that contains the list of different Pylint plugins
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So usually you have to search for them on pypi or just Google for them to find the interesting ones.