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https://github.com/reity/barriers

Python decorator for including/removing type checks, value/bounds checks, and other code blocks within the compiled bytecode of functions and methods.
https://github.com/reity/barriers

bounds-checking python python-decorators python-library python-syntax-converter python-testing type-checking

Last synced: 5 months ago
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Python decorator for including/removing type checks, value/bounds checks, and other code blocks within the compiled bytecode of functions and methods.

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README 

          
========

barriers

========



Python decorators for including/excluding type checks, value/bounds checks, and other code blocks within the compiled bytecode of functions and methods.



|pypi| |readthedocs| |actions| |coveralls|



.. |pypi| image:: https://badge.fury.io/py/barriers.svg

   :target: https://badge.fury.io/py/barriers

   :alt: PyPI version and link.



.. |readthedocs| image:: https://readthedocs.org/projects/barriers/badge/?version=latest

   :target: https://barriers.readthedocs.io/en/latest/?badge=latest

   :alt: Read the Docs documentation status.



.. |actions| image:: https://github.com/reity/barriers/workflows/lint-test-cover-docs/badge.svg

   :target: https://github.com/reity/barriers/actions/workflows/lint-test-cover-docs.yml

   :alt: GitHub Actions status.



.. |coveralls| image:: https://coveralls.io/repos/github/reity/barriers/badge.svg?branch=main

   :target: https://coveralls.io/github/reity/barriers?branch=main

   :alt: Coveralls test coverage summary.



Installation and Usage

----------------------

This library is available as a `package on PyPI `__:



.. code-block:: bash



    python -m pip install barriers



The library can be imported in the usual ways:



.. code-block:: python



    import barriers

    from barriers import barriers



Examples

^^^^^^^^



.. |barriers| replace:: ``barriers``

.. _barriers: https://barriers.readthedocs.io/en/1.1.0/_source/barriers.html#barriers.barriers.barriers



.. |globals| replace:: ``globals``

.. _globals: https://docs.python.org/3/library/functions.html#globals



Consider the function below (defined within a file ``f.py``). The body of this function contains a code block that raises an exception if either of the two inputs is a negative integer:



.. code-block:: python



    def f(x: int, y: int) -> int:



        if x < 0 or y < 0:

            raise ValueError('inputs must be nonnegative')



        return x + y



We can import the module above and invoke the function to observe its behavior:



.. code-block:: python



    >>> from f import f

    >>> f(1, 2)

    3

    >>> f(-1, -2)

    Traceback (most recent call last):

      ...

    ValueError: inputs must be nonnegative



An instance of the |barriers|_ class should normally be introduced near the top of a Python module using a pair of statements such as those below:



.. code-block:: python



    >>> from barriers import barriers

    >>> example = barriers(False) @ globals() # Remove marked code blocks (i.e., "disable barriers").



The |barriers|_ instance ``example`` defined above is a decorator that transforms any decorated function by removing any designated code blocks in the body of that function.



* The ``False`` argument in the expression ``barriers(False)`` above should be interpreted to mean that **this barrier is disabled** (*i.e.*, that the marked code blocks in the bodies of functions decorated by this decorator **should be removed**). The default value for this optional argument is ``True``; this should be interpreted to mean that **this barrier is enabled** (and, thus, that marked code blocks **should not be removed** from decorated functions).



* The notation ``@ globals()`` ensures that the namespace returned by |globals|_ is used when compiling the abstract syntax trees of transformed functions.



Consider the modified version of ``f.py`` below. A statement can be designated for automatic removal by placing a marker -- in this case, the ``example`` variable -- on the line directly above that statement. Note that in the body of the function ``f`` defined below, the ``if`` block is immediately preceded by a line that contains the variable ``example``:



.. code-block:: python



    from barriers import barriers

    example = barriers(False) @ globals()



    @example

    def f(x: int, y: int) -> int:



        example

        if x < 0 or y < 0:

            raise ValueError('inputs must be nonnegative')



        return x + y



The decorator ``@example`` automatically removes the ``if`` block in the function above. As a result, the function does not raise an exception when it is applied to negative inputs:



.. code-block:: python



    >>> from f import f

    >>> f(1, 2)

    3

    >>> f(-1, -2)

    -3



It is also possible to define and use individually named markers (which are created as attributes of the |barriers|_ instance):



.. code-block:: python



    >>> from barriers import barriers

    >>> checks = barriers(types=True, bounds=False) @ globals()



Given the above definitions, it is possible to introduce named markers such as those in the variant of ``f.py`` presented below. When a marker definition has been assigned ``True``, the statements immediately below that named marker **are not removed** (*i.e.*, the marked barrier statements are enabled). When a marker definition has been assigned ``False``, the corresponding marked statements **are removed**:



.. code-block:: python



    from barriers import barriers

    checks = barriers(types=True, bounds=False) @ globals()



    @checks

    def f(x: int, y: int) -> int:

    

        checks.types

        if not isinstance(x, int) and not isinstance(y, int):

            raise TypeError('inputs must be integers')

    

        checks.bounds

        if x < 0 or y < 0:

            raise ValueError('inputs must be nonnegative')

    

        return x + y



The described behavior can be observed when evaluating the function:



.. code-block:: python



    >>> from f import f

    >>> f('a', 'b')

    Traceback (most recent call last):

      ...

    TypeError: inputs must be integers

    >>> f(-1, -2)

    -3



Many additional details and examples are presented in the `documentation `__.



Development

-----------

All installation and development dependencies are fully specified in ``pyproject.toml``. The ``project.optional-dependencies`` object is used to `specify optional requirements `__ for various development tasks. This makes it possible to specify additional options (such as ``docs``, ``lint``, and so on) when performing installation using `pip `__:



.. code-block:: bash



    python -m pip install .[docs,lint]



Documentation

^^^^^^^^^^^^^

The documentation can be generated automatically from the source files using `Sphinx `__:



.. code-block:: bash



    python -m pip install .[docs]

    cd docs

    sphinx-apidoc -f -E --templatedir=_templates -o _source .. && make html



Testing and Conventions

^^^^^^^^^^^^^^^^^^^^^^^

All unit tests are executed and their coverage is measured when using `pytest `__ (see the ``pyproject.toml`` file for configuration details):



.. code-block:: bash



    python -m pip install .[test]

    python -m pytest



Alternatively, all unit tests are included in the module itself and can be executed using `doctest `__:



.. code-block:: bash



    python src/barriers/barriers.py -v



Style conventions are enforced using `Pylint `__:



.. code-block:: bash



    python -m pip install .[lint]

    python -m pylint src/barriers



Contributions

^^^^^^^^^^^^^

In order to contribute to the source code, open an issue or submit a pull request on the `GitHub page `__ for this library.



Versioning

^^^^^^^^^^

The version number format for this library and the changes to the library associated with version number increments conform with `Semantic Versioning 2.0.0 `__.



Publishing

^^^^^^^^^^

This library can be published as a `package on PyPI `__ by a package maintainer. First, install the dependencies required for packaging and publishing:



.. code-block:: bash



    python -m pip install .[publish]



Ensure that the correct version number appears in ``pyproject.toml``, and that any links in this README document to the Read the Docs documentation of this package (or its dependencies) have appropriate version numbers. Also ensure that the Read the Docs project for this library has an `automation rule `__ that activates and sets as the default all tagged versions. Create and push a tag for this version (replacing ``?.?.?`` with the version number):



.. code-block:: bash



    git tag ?.?.?

    git push origin ?.?.?



Remove any old build/distribution files. Then, package the source into a distribution archive:



.. code-block:: bash



    rm -rf build dist src/*.egg-info

    python -m build --sdist --wheel .



Finally, upload the package distribution archive to `PyPI `__:



.. code-block:: bash



    python -m twine upload dist/*