.. _reference_conanfile_methods_config_options:

config_options()
================

The ``config_options()`` method is used to configure or constrain the available options in a package **before** assigning them a value.
A typical use case is to remove an option in a given platform.
For example, the ``SSE2`` flag doesn't exist in architectures different than 32 bits, so it should be removed in this method like so:

.. code-block:: python

    def config_options(self):
        if self.settings.arch != "x86_64":
            del self.options.with_sse2

The ``config_options()`` method executes:
* Before calling the ``configure()`` method.
* Before assigning the ``options`` values.
* After ``settings`` are already defined.

.. _reference_conanfile_methods_config_options_implementations:

Available automatic implementations
+++++++++++++++++++++++++++++++++++

.. include:: ../../../common/experimental_warning.inc

When the ``config_options()`` method is not defined, Conan can automatically manage some
conventional options if specified in the
:ref:`implements<conan_conanfile_attributes_implements>` ConanFile attribute:

auto_shared_fpic
----------------

Options automatically managed:

- ``fPIC`` (True, False).

It can be added to the recipe like this:

.. code-block:: python
    
    from conan import ConanFile
        
    class Pkg(ConanFile):
        implements = ["auto_shared_fpic"]
        ...

Then, if no ``config_options()`` method is specified in the recipe, Conan will
automatically manage the fPIC setting in the ``config_options`` step like this:

.. code-block:: python

    if conanfile.settings.get_safe("os") == "Windows":
        conanfile.options.rm_safe("fPIC")

Be aware that adding this implementation to the recipe may also affect the
:ref:`configure<reference_conanfile_methods_configure_implementations>` step.

If you need to implement custom behaviors in your recipes but also need this logic, it
must be explicitly declared:

.. code-block:: python


    def config_options(self):
        if conanfile.settings.get_safe("os") == "Windows":
            conanfile.options.rm_safe("fPIC")
        if self.settings.arch != "x86_64":
            del self.options.with_sse2

.. seealso::

    - Follow the :ref:`tutorial about recipe configuration methods<tutorial_creating_configure>`.