doc/devel/api_changes.rst
.. _api_changes:
API consistency and stability are of great value; Therefore, API changes (e.g. signature changes, behavior changes, removals) will only be conducted if the added benefit is worth the effort of adapting existing code.
Because we are a visualization library, our primary output is the final visualization the user sees; therefore, the appearance of the figure is part of the API and any changes, either semantic or aesthetic, are backwards-incompatible API changes.
Every new function, parameter and attribute that is not explicitly marked as private (i.e., starts with an underscore) becomes part of Matplotlib's public API. As discussed above, changing the existing API is cumbersome. Therefore, take particular care when adding new API:
Mark helper functions and internal attributes as private by prefixing them with an underscore.
Carefully think about good names for your functions and variables.
Try to adopt patterns and naming conventions from existing parts of the Matplotlib API.
Consider making as many arguments keyword-only as possible. See also
API Evolution the Right Way -- Add Parameters Compatibly__.
__ https://emptysqua.re/blog/api-evolution-the-right-way/#adding-parameters
Visual changes are considered an API break. Therefore, we generally do not modify existing colormaps, color sequences, or styles.
We put a high bar on adding new colormaps and styles to prevent excessively growing them. While the decision is case-by-case, evaluation criteria include:
license-discussion).. _deprecation-guidelines:
API changes in Matplotlib have to be performed following the deprecation process below, except in very rare circumstances as deemed necessary by the development team. Generally API deprecation happens in two stages:
This ensures that users are notified before the change will take effect and thus prevents unexpected breaking of code.
Rules ^^^^^
meso release <pr-milestones> (e.g. 3.x)API consistency lead <https://matplotlib.org/governance/people.html>_ developer... _intro-deprecation:
Introduce deprecation ^^^^^^^^^^^^^^^^^^^^^
#. Create :ref:deprecation notice <api_whats_new>
#. If possible, issue a ~matplotlib.MatplotlibDeprecationWarning when the
deprecated API is used. There are a number of helper tools for this:
_api.warn_deprecated() for general deprecation warnings@_api.deprecated to deprecate classes, functions,
methods, or properties@_api.deprecate_privatize_attribute to annotate deprecation of
attributes while keeping the internal private version.@_api.delete_parameter, @_api.rename_parameter, and
@_api.make_keyword_onlyAll these helpers take a first parameter since, which should be set to the next point release, e.g. "3.x".
You can use standard rst cross references in alternative.
#. Make appropriate changes to the type hints in the associated .pyi file.
The general guideline is to match runtime reported behavior.
@_api.deprecated or @_api.deprecate_privatize_attribute
are generally kept during the expiry period, and thus no changes are needed on
introduction.@_api.rename_parameter or @_api.make_keyword_only
report the new (post deprecation) signature at runtime, and thus should be
updated on introduction.@_api.delete_parameter should include a default value hint
for the deleted parameter, even if it did not previously have one (e.g.
param: <type> = ...)... _expire-deprecation:
Expire deprecation ^^^^^^^^^^^^^^^^^^
#. Create :ref:deprecation announcement <api_whats_new>. For the content,
you can usually copy the deprecation notice and adapt it slightly.
#. Change the code functionality and remove any related deprecation warnings.
#. Make appropriate changes to the type hints in the associated .pyi file.
@_api.deprecated or @_api.deprecate_privatize_attribute
are to be removed on expiry.@_api.rename_parameter or @_api.make_keyword_only
will have been updated at introduction, and require no change now.@_api.delete_parameter will need to be updated to the
final signature, in the same way as the .py file signature is updated.ci/mypy-stubtest-allowlist.txt which indicate a deprecation
version should be double checked. In most cases this is not needed, though some
items were never type hinted in the first place and were added to this file
instead. For removed items that were not in the stub file, only deleting from the
allowlist is required... redirect-from:: /devel/coding_guide#new-features-and-api-changes
.. _api_whats_new:
When adding or changing the API in a backward in-compatible way, please add the
appropriate :ref:versioning directive <versioning-directives> and document it
for the release notes and add the entry to the appropriate folder:
+-------------------+-----------------------------+----------------------------------------------+
| | versioning directive | announcement folder |
+===================+=============================+==============================================+
| new feature | .. versionadded:: 3.N | :file:doc/users/next_whats_new/ |
+-------------------+-----------------------------+----------------------------------------------+
| API change | .. versionchanged:: 3.N | :file:doc/api/next_api_changes/[kind] |
+-------------------+-----------------------------+----------------------------------------------+
When deprecating API, please add a notice as described in the
:ref:deprecation guidelines <deprecation-guidelines> and summarized here:
+--------------------------------------------------+----------------------------------------------+
| stage | announcement folder |
+===========+======================================+==============================================+
| :ref:introduce deprecation <intro-deprecation> | :file:doc/api/next_api_changes/deprecation |
+-----------+--------------------------------------+----------------------------------------------+
| :ref:expire deprecation <expire-deprecation> | :file:doc/api/next_api_changes/[kind] |
+-----------+--------------------------------------+----------------------------------------------+
Generally the introduction notices can be repurposed for the expiration notice as they are expected to be describing the same API changes and removals.
.. _versioning-directives:
Versioning directives ^^^^^^^^^^^^^^^^^^^^^
When making a backward incompatible change, please add a versioning directive in the docstring. The directives should be placed at the end of a description block. For example::
class Foo: """ This is the summary.
Followed by a longer description block.
Consisting of multiple lines and paragraphs.
.. versionadded:: 3.5
Parameters
----------
a : int
The first parameter.
b: bool, default: False
This was added later.
.. versionadded:: 3.6
"""
def set_b(b):
"""
Set b.
.. versionadded:: 3.6
Parameters
----------
b: bool
For classes and functions, the directive should be placed before the Parameters section. For parameters, the directive should be placed at the end of the parameter description. The micro release version is omitted and the directive should not be added to entire modules.
Release notes ^^^^^^^^^^^^^
For both change notes and what's new, please avoid using cross-references in section titles as it causes links to be confusing in the table of contents. Instead, ensure that a cross-reference is included in the descriptive text.
.. _api-change-notes:
API change notes """"""""""""""""
.. include:: ../api/next_api_changes/README.rst :start-after: api-change-guide-start :end-before: api-change-guide-end
.. _whats-new-notes:
What's new notes """"""""""""""""
.. include:: ../users/next_whats_new/README.rst :start-after: whats-new-guide-start :end-before: whats-new-guide-end