Add a new extension: sphinx.ext.autodoc.typehints

Author: tk0miya

CHANGES

@@ -42,6 +42,10 @@ Features added
 * SphinxTranslator now calls visitor/departure method for super node class if
   visitor/departure method for original node class not found
 * #6418: Add new event: :event:`object-description-transform`
+* #6418: autodoc: Add a new extension ``sphinx.ext.autodoc.typehints``. It shows
+  typehints as object description if ``autodoc_typehints = "description"`` set.
+  This is an experimental extension and it will be integrated into autodoc in
+  Sphinx-3.0.
 
 Bugs fixed
 ----------

doc/usage/extensions/autodoc.rst

@@ -567,3 +567,24 @@ member should be included in the documentation by using the following event:
       ``inherited_members``, ``undoc_members``, ``show_inheritance`` and
       ``noindex`` that are true if the flag option of same name was given to the
       auto directive
+
+Generating documents from type annotations
+------------------------------------------
+
+As an experimental feature, autodoc provides ``sphinx.ext.autodoc.typehints`` as
+an additional extension.  It extends autodoc itself to generate function document
+from its type annotations.
+
+To enable the feature, please add ``sphinx.ext.autodoc.typehints`` to list of
+extensions and set `'description'` to :confval:`autodoc_typehints`:
+
+.. code-block:: python
+
+   extensions = ['sphinx.ext.autodoc', 'sphinx.ext.autodoc.typehints']
+
+   autodoc_typehints = 'description'
+
+.. versionadded:: 2.4
+
+   Added as an experimental feature.  This will be integrated into autodoc core
+   in Sphinx-3.0.

sphinx/ext/autodoc/typehints.py

@@ -0,0 +1,144 @@
+"""
+    sphinx.ext.autodoc.typehints
+    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+    Generating content for autodoc using typehints
+
+    :copyright: Copyright 2007-2020 by the Sphinx team, see AUTHORS.
+    :license: BSD, see LICENSE for details.
+"""
+
+import re
+from typing import Any, Dict, Iterable
+from typing import cast
+
+from docutils import nodes
+from docutils.nodes import Element
+
+from sphinx import addnodes
+from sphinx.application import Sphinx
+from sphinx.config import ENUM
+from sphinx.util import inspect, typing
+
+
+def config_inited(app, config):
+    if config.autodoc_typehints == 'description':
+        # HACK: override this to make autodoc suppressing typehints in signatures
+        config.autodoc_typehints = 'none'
+
+        # preserve user settings
+        app._autodoc_typehints_description = True
+    else:
+        app._autodoc_typehints_description = False
+
+
+def record_typehints(app: Sphinx, objtype: str, name: str, obj: Any,
+                     options: Dict, args: str, retann: str) -> None:
+    """Record type hints to env object."""
+    try:
+        if callable(obj):
+            annotations = app.env.temp_data.setdefault('annotations', {}).setdefault(name, {})
+            sig = inspect.signature(obj)
+            for param in sig.parameters.values():
+                if param.annotation is not param.empty:
+                    annotations[param.name] = typing.stringify(param.annotation)
+            if sig.return_annotation is not sig.empty:
+                annotations['return'] = typing.stringify(sig.return_annotation)
+    except TypeError:
+        pass
+
+
+def merge_typehints(app: Sphinx, domain: str, objtype: str, contentnode: Element) -> None:
+    if domain != 'py':
+        return
+    if app._autodoc_typehints_description is False:  # type: ignore
+        return
+
+    signature = cast(addnodes.desc_signature, contentnode.parent[0])
+    fullname = '.'.join([signature['module'], signature['fullname']])
+    annotations = app.env.temp_data.get('annotations', {})
+    if annotations.get(fullname, {}):
+        field_lists = [n for n in contentnode if isinstance(n, nodes.field_list)]
+        if field_lists == []:
+            field_list = insert_field_list(contentnode)
+            field_lists.append(field_list)
+
+        for field_list in field_lists:
+            modify_field_list(field_list, annotations[fullname])
+
+
+def insert_field_list(node: Element) -> nodes.field_list:
+    field_list = nodes.field_list()
+    desc = [n for n in node if isinstance(n, addnodes.desc)]
+    if desc:
+        # insert just before sub object descriptions (ex. methods, nested classes, etc.)
+        index = node.index(desc[0])
+        node.insert(index - 1, [field_list])
+    else:
+        node += field_list
+
+    return field_list
+
+
+def modify_field_list(node: nodes.field_list, annotations: Dict[str, str]) -> None:
+    arguments = {}  # type: Dict[str, Dict[str, bool]]
+    fields = cast(Iterable[nodes.field], node)
+    for field in fields:
+        field_name = field[0].astext()
+        parts = re.split(' +', field_name)
+        if parts[0] == 'param':
+            if len(parts) == 2:
+                # :param xxx:
+                arg = arguments.setdefault(parts[1], {})
+                arg['param'] = True
+            elif len(parts) > 2:
+                # :param xxx yyy:
+                name = ' '.join(parts[2:])
+                arg = arguments.setdefault(name, {})
+                arg['param'] = True
+                arg['type'] = True
+        elif parts[0] == 'type':
+            name = ' '.join(parts[1:])
+            arg = arguments.setdefault(name, {})
+            arg['type'] = True
+        elif parts[0] == 'rtype':
+            arguments['return'] = {'type': True}
+
+    for name, annotation in annotations.items():
+        if name == 'return':
+            continue
+
+        arg = arguments.get(name, {})
+        field = nodes.field()
+        if arg.get('param') and arg.get('type'):
+            # both param and type are already filled manually
+            continue
+        elif arg.get('param'):
+            # only param: fill type field
+            field += nodes.field_name('', 'type ' + name)
+            field += nodes.field_body('', nodes.paragraph('', annotation))
+        elif arg.get('type'):
+            # only type: It's odd...
+            field += nodes.field_name('', 'param ' + name)
+            field += nodes.field_body('', nodes.paragraph('', ''))
+        else:
+            # both param and type are not found
+            field += nodes.field_name('', 'param ' + annotation + ' ' + name)
+            field += nodes.field_body('', nodes.paragraph('', ''))
+
+        node += field
+
+    if 'return' in annotations and 'return' not in arguments:
+        field = nodes.field()
+        field += nodes.field_name('', 'rtype')
+        field += nodes.field_body('', nodes.paragraph('', annotation))
+        node += field
+
+
+def setup(app):
+    app.setup_extension('sphinx.ext.autodoc')
+    app.config.values['autodoc_typehints'] = ('signature', True,
+                                              ENUM("signature", "description", "none"))
+    app.connect('config-inited', config_inited)
+    app.connect('autodoc-process-signature', record_typehints)
+    app.connect('object-description-transform', merge_typehints)

sphinx/util/inspect.py

@@ -450,6 +450,8 @@ class Signature:
     its return annotation.
     """
 
+    empty = inspect.Signature.empty
+
     def __init__(self, subject: Callable, bound_method: bool = False,
                  has_retval: bool = True) -> None:
         warnings.warn('sphinx.util.inspect.Signature() is deprecated',

tests/roots/test-ext-autodoc/index.rst

@@ -7,3 +7,5 @@
 
 .. automodule:: autodoc_dummy_bar
    :members:
+
+.. autofunction:: target.typehints.incr

tests/test_ext_autodoc_configs.py

@@ -540,6 +540,24 @@ def test_autodoc_typehints_none(app):
     ]
 
 
+@pytest.mark.sphinx('text', testroot='ext-autodoc',
+                    confoverrides={'extensions': ['sphinx.ext.autodoc.typehints'],
+                                   'autodoc_typehints': 'description'})
+def test_autodoc_typehints_description(app):
+    app.build()
+    context = (app.outdir / 'index.txt').text()
+    assert ('target.typehints.incr(a, b=1)\n'
+            '\n'
+            '   Parameters:\n'
+            '      * **a** (*int*) --\n'
+            '\n'
+            '      * **b** (*int*) --\n'
+            '\n'
+            '   Return type:\n'
+            '      int\n'
+            in context)
+
+
 @pytest.mark.sphinx('html', testroot='ext-autodoc')
 @pytest.mark.filterwarnings('ignore:autodoc_default_flags is now deprecated.')
 def test_merge_autodoc_default_flags1(app):