httk.core.requirements
======================

.. py:module:: httk.core.requirements

.. autoapi-nested-parse::

   Parse and check minimum-version requirements on installed distributions.

   Manifests declare ``requires = ["httk-workflow>=2.2.0", ...]``. Only the
   ``>=`` operator is supported, with a plain release ``N(.N)*`` on the right.
   Installed versions are compared in PEP 440 order without a ``packaging``
   dependency: a pre or dev release of the required release does not satisfy
   it, while a post release or local label does.



Exceptions
----------

.. autoapisummary::

   httk.core.requirements.RequirementError


Classes
-------

.. autoapisummary::

   httk.core.requirements.Requirement


Functions
---------

.. autoapisummary::

   httk.core.requirements.parse_requirements
   httk.core.requirements.unmet_requirements
   httk.core.requirements.check_requirements


Module Contents
---------------

.. py:exception:: RequirementError

   Bases: :py:obj:`ValueError`


   Report that installed distributions do not meet declared requirements.


.. py:class:: Requirement

   Describe one minimum-version requirement.

   :param name: Name the distribution, normalized per PEP 503.
   :param minimum: Give the minimum release segments.
   :param text: Give the requirement as declared, without whitespace.


   .. py:attribute:: name
      :type:  str


   .. py:attribute:: minimum
      :type:  tuple[int, ...]


   .. py:attribute:: text
      :type:  str


.. py:function:: parse_requirements(values, where)

   Parse a ``requires`` list of ``NAME>=VERSION`` strings.

   :param values: Supply the raw manifest value.
   :param where: Name the manifest key in error messages.
   :return: The parsed requirements in declaration order.
   :raises ValueError: If the value is not a list of valid, distinct requirement strings.


.. py:function:: unmet_requirements(requirements)

   Describe the requirements the running interpreter does not meet.

   :param requirements: Check these requirements.
   :return: One message per unmet requirement, e.g. ``"httk-workflow>=2.2.0 (installed: 2.1.1)"``.


.. py:function:: check_requirements(requirements, what)

   Require every requirement to be met by the running interpreter.

   :param requirements: Check these requirements.
   :param what: Name the requiring manifest in the error message.
   :raises RequirementError: If any requirement is unmet; the message lists every one.