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https://github.com/seddonym/layer_linter

This package is deprecated - use Import Linter instead.
https://github.com/seddonym/layer_linter

Last synced: 13 days ago
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This package is deprecated - use Import Linter instead.

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README 

        
============

Layer Linter

============



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**Layer Linter has been deprecated in favour of Import Linter.**



`Import Linter`_ does everything Layer Linter does, but with more features and a slightly different API.

If you're already using Layer Linter, migrating to Import Linter is simple: there is a guide here_.



Outline

-------



Layer Linter checks that your project follows a custom-defined layered architecture, based on

its internal dependencies (i.e. the imports between its modules).



* Free software: BSD license

* Documentation: https://layer-linter.readthedocs.io.



.. _Import Linter: https://github.com/seddonym/import-linter

.. _here: https://layer-linter.readthedocs.io/en/latest/migrating-to-import-linter.html



Overview

--------



Layer Linter is a command line tool to check that you are following a self-imposed

architecture within your Python project. It does this by analysing the internal

imports between all the modules in your code base, and compares this

against a set of simple rules that you provide in a ``layers.yml`` file.



For example, you can use it to check that no modules inside ``myproject.foo``

import from any modules inside ``myproject.bar``, even indirectly.



This is particularly useful if you are working on a complex codebase within a team,

when you want to enforce a particular architectural style. In this case you can add

Layer Linter to your deployment pipeline, so that any code that does not follow

the architecture will fail tests.



Quick start

-----------



Install Layer Linter::



    pip install layer-linter



Decide on the dependency flows you wish to check. In this example, we have

organised our project into three subpackages, ``myproject.high``, ``myproject.medium``

and ``myproject.low``. These subpackages are known as *layers*. Note: layers must

have the same parent package (i.e. all be in the same directory). This parent is known as a *container*.



Create a ``layers.yml`` in the root of your project. For example::



    My Layers Contract:

      containers:

        - myproject

      layers:

        - high

        - medium

        - low



(This contract tells Layer Linter that the order of the layers runs from ``low`` at the bottom

to ``high`` at the top. Layers higher up can import ones lower down, but not the other way around.)



Note that the container is an absolute name of a Python package, while the layers are relative to the container.



Now, from your project root, run::



    layer-lint myproject



If your code violates the contract, you will see an error message something like this::



    ============

    Layer Linter

    ============



    ---------

    Contracts

    ---------



    Analyzed 23 files, 44 dependencies.

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



    My layer contract BROKEN



    Contracts: 0 kept, 1 broken.



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

    Broken contracts

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



    My layer contract

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



    1. myproject.low.x imports myproject.high.y:



        myproject.low.x <-

        myproject.utils <-

        myproject.high.y



For more details, see `Usage`_.



.. _Usage: https://layer-linter.readthedocs.io/en/latest/usage.html