:mod:`cloup.constraints.conditions`
===================================

.. py:module:: cloup.constraints.conditions

.. autoapi-nested-parse::

   This modules contains described predicates that you can use as conditions of
   conditional constraints (see :class:`cloup.constraints.If`).

   Predicates should be treated as immutable objects, even though immutability
   is not (at the moment) enforced.





                              

Classes summary
---------------

.. autosummary::

   ~cloup.constraints.conditions.Predicate
   ~cloup.constraints.conditions.Not
   ~cloup.constraints.conditions.IsSet
   ~cloup.constraints.conditions.Equal



                                           
Contents
--------
.. data:: P
   

   

.. class:: Predicate

   Bases: :py:obj:`abc.ABC`

   A ``Callable`` that takes a ``Context`` and returns a boolean, with an
   associated description. Meant to be used as condition in a conditional
   constraint (see :class:`~cloup.constraints.If`).

   .. method:: description(self, ctx)
      :abstractmethod:

      Succint description of the predicate (alias: `desc`).


   .. method:: negated_description(self, ctx)

      Succint description of the negation of this predicate (alias: `neg_desc`).


   .. method:: desc(self, ctx)

      Short alias for :meth:`description`.


   .. method:: neg_desc(self, ctx)

      Short alias for :meth:`negated_description`.


   .. method:: negated(self)


   .. method:: __call__(self, ctx)
      :abstractmethod:

      Evaluate the predicate on the given context.


   .. method:: __invert__(self)


   .. method:: __or__(self, other)


   .. method:: __and__(self, other)


   .. method:: __repr__(self)

      Return repr(self).



.. class:: Not(predicate)


   Bases: :py:obj:`Predicate`, :py:obj:`Generic`\ [\ :py:obj:`P`\ ]

   A ``Callable`` that takes a ``Context`` and returns a boolean, with an
   associated description. Meant to be used as condition in a conditional
   constraint (see :class:`~cloup.constraints.If`).

   .. method:: description(self, ctx)

      Succint description of the predicate (alias: `desc`).


   .. method:: negated_description(self, ctx)

      Succint description of the negation of this predicate (alias: `neg_desc`).


   .. method:: __call__(self, ctx)

      Evaluate the predicate on the given context.


   .. method:: __invert__(self)


   .. method:: __repr__(self)

      Return repr(self).



.. class:: IsSet(param_name)


   Bases: :py:obj:`Predicate`

   A ``Callable`` that takes a ``Context`` and returns a boolean, with an
   associated description. Meant to be used as condition in a conditional
   constraint (see :class:`~cloup.constraints.If`).

   .. method:: description(self, ctx)

      Succint description of the predicate (alias: `desc`).


   .. method:: negated_description(self, ctx)

      Succint description of the negation of this predicate (alias: `neg_desc`).


   .. method:: __call__(self, ctx)

      Evaluate the predicate on the given context.



.. class:: Equal(param_name, value)


   Bases: :py:obj:`Predicate`

   True if the parameter value equals ``value``.

   .. method:: description(self, ctx)

      Succint description of the predicate (alias: `desc`).


   .. method:: negated_description(self, ctx)

      Succint description of the negation of this predicate (alias: `neg_desc`).


   .. method:: __call__(self, ctx)

      Evaluate the predicate on the given context.