VSCode Linter Config for Python

VSCode allows both explicit setting config file and implicit setting by typing “command + ,”, which sometimes confusing (for example, which root is the implicit setting applied to or which setting should we use to enable some functionality). Here is a guide for how to config VSCode for python syntax highlight and type checking.

Import Path

If you are not working at the root directory (the directory that you opened in open project tab) or you are not using the python in your local machine (for example, in a virtual env using pyenv), Pylance sometimes complains about the missing imports for librarys that has been already installed. To help Pylance find the library, first ensure that the version of the python is the same as the one you are working with. You can change which python you are using in the bottom bar of VSCode and to check which python you are using, simply type:

which python

Then, add this setting to ./vscode/setting.json:

"python.analysis.useImportHeuristic": true

It looks like gray that vscode doesn’t really use it, but it would work as this config is embedded in VSCode, even though it does not exposed to the user.

Now you can check whether you provide the correct import, but how about type checking. As we know, Python 3 provide explicit type annotation to provide a better experience of how to use the function and potentially prevent misuse of variables (although the intepreter won’t enforce type checking). An example of type hint looks like this:

def test_sample(
    id: int = 0, # default
    name: str,
    isValid: bool,
    child: Child, # custom type also works
) -> Result : # return type
    pass

In order to perform a type checking in VSCode, we can use mypy extension in VSCode. You can download it from the VSCode store. After installation, install mypy using pip and set the dmypy executable using:

"mypy.dmypyExecutable": "/path/to/your/dmypy/exec"

as well as enable Pylance to lint your codes in setting:

• python.languageServer = Pylance
• python.linting = enabled

Though mypy is useful, it cannot check everything. For example, if you use types-attrs to create a new class, mypy cannot check the parameters.