Mypy plugin for PYLSP
======================

.. image:: https://badge.fury.io/py/pylsp-mypy.svg
    :target: https://badge.fury.io/py/pylsp-mypy

.. image:: https://github.com/python-lsp/pylsp-mypy/workflows/Python%20package/badge.svg?branch=master
    :target: https://github.com/python-lsp/pylsp-mypy/

This is a plugin for the `Python LSP Server`_.

.. _`Python LSP Server`: https://github.com/python-lsp/python-lsp-server

It, like `mypy`_, requires Python 3.10 or newer.

.. _`mypy`: https://github.com/python/mypy


Installation
------------

Install into the same virtualenv as python-lsp-server itself.

``pip install pylsp-mypy``

Configuration
-------------
``pylsp-mypy`` supports the use of ``pyproject.toml`` for configuration. It can also be configuered using configs provided to the LSP server. The configuration keys are listed in the following.

.. list-table:: Configuration
   :header-rows: 1

   * - ``pyproject.toml`` key
     - LSP Configuration Key
     - Type
     - Description
     - Default
   * - ``live_mode``
     - ``pylsp.plugins.pylsp_mypy.live_mode``
     - ``boolean``
     - **Provides type checking as you type**. This writes to a tempfile every time a check is done. Turning off ``live_mode`` means you must save your changes for mypy diagnostics to update correctly.
     - true
   * - ``dmypy``
     - ``pylsp.plugins.pylsp_mypy.dmypy``
     - ``boolean``
     - **Executes via** ``dmypy run`` **rather than** ``mypy``. This uses the ``dmypy`` daemon and may dramatically improve the responsiveness of the ``pylsp`` server, however this currently does not work in ``live_mode``. Enabling this disables ``live_mode``, even for conflicting configs.
     - false
   * - ``strict``
     - ``pylsp.plugins.pylsp_mypy.strict``
     - ``boolean``
     - **Refers to the** ``strict`` **option of** ``mypy``. This option often is too strict to be useful.
     - false
   * - ``overrides``
     - ``pylsp.plugins.pylsp_mypy.overrides``
     - ``array`` of (``string`` items or ``true``)
     - **A list of alternate or supplemental command-line options**. This modifies the options passed to ``mypy`` or the mypy-specific ones passed to ``dmypy run``. When present, the special boolean member ``true`` is replaced with the command-line options that would've been passed had ``overrides`` not been specified.
     - ``[true]``
   * - ``dmypy_status_file``
     - ``pylsp.plugins.pylsp_mypy.dmypy_status_file``
     - ``string``
     - **Specifies which status file dmypy should use**. This modifies the ``--status-file`` option passed to ``dmypy`` given ``dmypy`` is active.
     - ``.dmypy.json``
   * - ``config_sub_paths``
     - ``pylsp.plugins.pylsp_mypy.config_sub_paths``
     - ``array`` of ``string`` items
     - **Specifies sub paths under which the mypy configuration file may be found**. For each directory searched for the mypy config file, this also searches the sub paths specified here.
     - ``[]``
   * - ``report_progress``
     - ``pylsp.plugins.pylsp_mypy.report_progress``
     - ``boolean``
     - **Report basic progress to the LSP client**. With this option, pylsp-mypy will report when mypy is running, given your editor supports LSP progress reporting. For small files this might produce annoying flashing in your editor, especially in ``live_mode``. For large projects, enabling this can be helpful to assure yourself whether mypy is still running.
     - false
   * - ``exclude``
     - ``pylsp.plugins.pylsp_mypy.exclude``
     - ``array`` of ``string`` items
     - **A list of regular expressions which should be ignored**. The ``mypy`` runner wil not be invoked when a document path is matched by one of the expressions. Note that this differs from the ``exclude`` directive of a ``mypy`` config which is only used for recursively discovering files when mypy is invoked on a whole directory. For both windows or unix platforms you should use forward slashes (``/``) to indicate paths.
     - ``[]``
   * - ``follow-imports``
     - ``pylsp.plugins.pylsp_mypy.follow-imports``
     - ``normal``, ``silent``, ``skip`` or ``error``
     - ``mypy`` **parameter** ``follow-imports``. In ``mypy`` this is ``normal`` by default. We set it ``silent``, to sort out unwanted results. This can cause cache invalidation if you also run ``mypy`` in other ways. Setting this to ``normal`` avoids this at the cost of a small performance penalty.
     - ``silent``
   * - ``mypy_command``
     - ``pylsp.plugins.pylsp_mypy.mypy_command``
     - ``array`` of ``string`` items
     - **The command to run mypy**. This is useful if you want to run mypy in a specific virtual environment. Requires env variable ``PYLSP_MYPY_ALLOW_DANGEROUS_CODE_EXECUTION`` to be set.
     - ``[]``
   * - ``dmypy_command``
     - ``pylsp.plugins.pylsp_mypy.dmypy_command``
     - ``array`` of ``string`` items
     - **The command to run dmypy**. This is useful if you want to run dmypy in a specific virtual environment. Requires env variable ``PYLSP_MYPY_ALLOW_DANGEROUS_CODE_EXECUTION`` to be set.
     - ``[]``

Both ``mypy_command`` and ``dmypy_command`` could be used by a malicious repo to execute arbitrary code by looking at its source with this plugin active.
Still users want this feature. For security reasons this is disabled by default. If you really want it and accept the risks set the environment variable ``PYLSP_MYPY_ALLOW_DANGEROUS_CODE_EXECUTION`` in order to activate it.

Using a ``pyproject.toml`` for configuration, which is in fact the preferred way, your configuration could look like this:

::

    [tool.pylsp-mypy]
    enabled = true
    live_mode = true
    strict = true
    exclude = ["tests/*"]

A ``pyproject.toml`` does not conflict with the legacy config file (deprecated) given that it does not contain a ``pylsp-mypy`` section. The following explanation uses the syntax of the legacy config file (deprecated). However, all these options also apply to the ``pyproject.toml`` configuration (note the lowercase bools).
Depending on your editor, the configuration (found in a file called ``pylsp-mypy.cfg`` in your workspace or a parent directory) should be roughly like this for a standard configuration:

::

    {
        "enabled": True,
        "live_mode": True,
        "strict": False,
        "exclude": ["tests/*"]
    }

With ``dmypy`` enabled your config should look like this:

::

    {
        "enabled": True,
        "live_mode": False,
        "dmypy": True,
        "strict": False
    }

With ``overrides`` specified (for example to tell mypy to use a different python than the currently active venv), your config could look like this:

::

    {
        "enabled": True,
        "overrides": ["--python-executable", "/home/me/bin/python", True]
    }

With ``dmypy_status_file`` your config could look like this:

::

    {
        "enabled": True,
        "live_mode": False,
        "dmypy": True,
        "strict": False,
        "dmypy_status_file": ".custom_dmypy_status_file.json"
    }

With ``config_sub_paths`` your config could look like this:

::

    {
        "enabled": True,
        "config_sub_paths": [".config"]
    }

With ``report_progress`` your config could look like this:

::

    {
        "enabled": True,
        "report_progress": True
    }

With ``mypy_command`` your config could look like this:

::

    {
        "enabled": True,
        "mypy_command": ["poetry", "run", "mypy"]
    }

With ``dmypy_command`` your config could look like this:

::

    {
        "enabled": True,
        "live_mode": False,
        "dmypy": True,
        "dmypy_command": ["/path/to/venv/bin/dmypy"]
    }

Developing
-------------

Install development dependencies with (you might want to create a virtualenv first):

::

   pip install -r requirements.txt

The project is formatted with `black`_. You can either configure your IDE to automatically format code with it, run it manually (``black .``) or rely on pre-commit (see below) to format files on git commit.

The project is formatted with `isort`_. You can either configure your IDE to automatically sort imports with it, run it manually (``isort .``) or rely on pre-commit (see below) to sort files on git commit.

The project uses two rst tests in order to assure uploadability to pypi: `rst-linter`_ as a pre-commit hook and `rstcheck`_ in a GitHub workflow. This does not catch all errors.

This project uses `pre-commit`_ to enforce code-quality. After cloning the repository install the pre-commit hooks with:

::

   pre-commit install

After that pre-commit will run `all defined hooks`_ on every ``git commit`` and keep you from committing if there are any errors.

.. _black: https://github.com/psf/black
.. _isort: https://github.com/PyCQA/isort
.. _rst-linter: https://github.com/Lucas-C/pre-commit-hooks-markup
.. _rstcheck: https://github.com/myint/rstcheck
.. _pre-commit: https://pre-commit.com/
.. _all defined hooks: .pre-commit-config.yaml
