A flake8 <https://flake8.readthedocs.io/>_ plugin that finds improvements for raise statements.

Install using pip:

.. code-block:: sh

$ pip install flake8-raise

When installed, the plugin will automatically be used by flake8. To check it is installed correctly, run flake8 --version and look in the list of installed plugins:

.. code-block:: sh

$ flake8 --version
3.7.9 (flake8-raise: 0.0.5, mccabe: 0.6.1, pycodestyle: 2.5.0, pyflakes: 2.1.1) CPython 3.8.1 on Linux

==== ==== Code Rule ==== ==== R100 raise in except handler without from R101 use bare raise in except handler R102 unnecessary parentheses on raised exception ==== ====

R100 raise in except handler without from

.. code-block:: py

    try:
        foo["bar"]
    except KeyError:
        raise MyException

Will result in the error:

.. code-block:: text

    R100 raise in except handler without from.

To fix, change to:

.. code-block:: py

    try:
        foo['bar']
    except KeyError as e:
        raise MyException from e

R101 use bare ``raise`` in ``except`` handler
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: py

    try:
        foo["bar"]
    except KeyError as e:
        raise e

Will result in the error:

.. code-block:: text

    R101 Use bare raise in except handler.

To fix, change to:

.. code-block:: py

    try:
        foo['bar']
    except KeyError:
        raise

R102 unnecessary parentheses on raised exception
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: py

    raise TypeError()

Will result in the error:

.. code-block:: text

    R102 unnecessary parentheses on raised exception

To fix, change to:

.. code-block:: py

    raise TypeError