Improve handling for overriding extractors with plugins (#5916)

* Extractors replaced with plugin extractors now show in debug output
* Better testcase handling
* Added documentation
Authored by: coletdjnz, pukkandan

README.md

@@ -1841,7 +1841,7 @@ ## Installing Plugins
     * Source: where `<root-dir>/yt_dlp/__main__.py`, `<root-dir>/yt-dlp-plugins/<package name>/yt_dlp_plugins/`
 
 3. **pip and other locations in `PYTHONPATH`**
-    * Plugin packages can be installed and managed using `pip`. See [ytdlp-sample-plugins](https://github.com/yt-dlp/yt-dlp-sample-plugins) for an example.
+    * Plugin packages can be installed and managed using `pip`. See [yt-dlp-sample-plugins](https://github.com/yt-dlp/yt-dlp-sample-plugins) for an example.
       * Note: plugin files between plugin packages installed with pip must have unique filenames
     * Any path in `PYTHONPATH` is searched in for the `yt_dlp_plugins` namespace folder.
       * Note: This does not apply for Pyinstaller/py2exe builds.
@@ -1854,9 +1854,12 @@ ## Installing Plugins
 
 ## Developing Plugins
 
-See [ytdlp-sample-plugins](https://github.com/yt-dlp/yt-dlp-sample-plugins) for a sample plugin package with instructions on how to set up an environment for plugin development. 
+See [yt-dlp-sample-plugins](https://github.com/yt-dlp/yt-dlp-sample-plugins) for a sample plugin package with instructions on how to set up an environment for plugin development. 
 
-All public classes with a name ending in `IE` are imported from each file. This respects underscore prefix (e.g. `_MyBasePluginIE` is private) and `__all__`. Modules can similarly be excluded by prefixing the module name with an underscore (e.g. `_myplugin.py`)
+All public classes with a name ending in `IE`/`PP` are imported from each file for extractors and postprocessors repectively. This respects underscore prefix (e.g. `_MyBasePluginIE` is private) and `__all__`. Modules can similarly be excluded by prefixing the module name with an underscore (e.g. `_myplugin.py`)
+
+To replace an existing extractor with a subclass of one, set the `plugin_name` class keyword argument (e.g. `MyPluginIE(ABuiltInIE, plugin_name='myplugin')` will replace `ABuiltInIE` with `MyPluginIE`). 
+Due to the mechanics behind this, you should exclude the subclass extractor from being imported separately by making it private using one of the methods described above.
 
 If you are a plugin author, add [yt-dlp-plugins](https://github.com/topics/yt-dlp-plugins) as a topic to your repository for discoverability
 

yt_dlp/YoutubeDL.py

@@ -33,7 +33,7 @@
 from .extractor.openload import PhantomJSwrapper
 from .minicurses import format_text
 from .plugins import directories as plugin_directories
-from .postprocessor import _PLUGIN_CLASSES as plugin_postprocessors
+from .postprocessor import _PLUGIN_CLASSES as plugin_pps
 from .postprocessor import (
     EmbedThumbnailPP,
     FFmpegFixupDuplicateMoovPP,
@@ -3730,7 +3730,10 @@ def print_debug_header(self):
 
         # These imports can be slow. So import them only as needed
         from .extractor.extractors import _LAZY_LOADER
-        from .extractor.extractors import _PLUGIN_CLASSES as plugin_extractors
+        from .extractor.extractors import (
+            _PLUGIN_CLASSES as plugin_ies,
+            _PLUGIN_OVERRIDES as plugin_ie_overrides
+        )
 
         def get_encoding(stream):
             ret = str(getattr(stream, 'encoding', 'missing (%s)' % type(stream).__name__))
@@ -3808,12 +3811,17 @@ def get_encoding(stream):
                 proxy_map.update(handler.proxies)
         write_debug(f'Proxy map: {proxy_map}')
 
-        for plugin_type, plugins in {'Extractor': plugin_extractors, 'Post-Processor': plugin_postprocessors}.items():
+        for plugin_type, plugins in {'Extractor': plugin_ies, 'Post-Processor': plugin_pps}.items():
-            if not plugins:
+            display_list = ['%s%s' % (
-                continue
-            write_debug(f'{plugin_type} Plugins: %s' % (', '.join(sorted(('%s%s' % (
                 klass.__name__, '' if klass.__name__ == name else f' as {name}')
-                for name, klass in plugins.items())))))
+                for name, klass in plugins.items()]
+            if plugin_type == 'Extractor':
+                display_list.extend(f'{plugins[-1].IE_NAME.partition("+")[2]} ({parent.__name__})'
+                                    for parent, plugins in plugin_ie_overrides.items())
+            if not display_list:
+                continue
+            write_debug(f'{plugin_type} Plugins: {", ".join(sorted(display_list))}')
+
         plugin_dirs = plugin_directories()
         if plugin_dirs:
             write_debug(f'Plugin directories: {plugin_dirs}')

yt_dlp/extractor/common.py

@@ -3442,13 +3442,17 @@ def get_testcases(cls, include_onlymatching=False):
                 continue
             t['name'] = cls.ie_key()
             yield t
+        if getattr(cls, '__wrapped__', None):
+            yield from cls.__wrapped__.get_testcases(include_onlymatching)
 
     @classmethod
     def get_webpage_testcases(cls):
         tests = vars(cls).get('_WEBPAGE_TESTS', [])
         for t in tests:
             t['name'] = cls.ie_key()
-        return tests
+            yield t
+        if getattr(cls, '__wrapped__', None):
+            yield from cls.__wrapped__.get_webpage_testcases()
 
     @classproperty(cache=True)
     def age_limit(cls):
@@ -3710,10 +3714,12 @@ def __init_subclass__(cls, *, plugin_name=None, **kwargs):
         if plugin_name:
             mro = inspect.getmro(cls)
             super_class = cls.__wrapped__ = mro[mro.index(cls) + 1]
-            cls.IE_NAME, cls.ie_key = f'{super_class.IE_NAME}+{plugin_name}', super_class.ie_key
+            cls.PLUGIN_NAME, cls.ie_key = plugin_name, super_class.ie_key
+            cls.IE_NAME = f'{super_class.IE_NAME}+{plugin_name}'
             while getattr(super_class, '__wrapped__', None):
                 super_class = super_class.__wrapped__
             setattr(sys.modules[super_class.__module__], super_class.__name__, cls)
+            _PLUGIN_OVERRIDES[super_class].append(cls)
 
         return super().__init_subclass__(**kwargs)
 
@@ -3770,3 +3776,6 @@ class UnsupportedURLIE(InfoExtractor):
 
     def _real_extract(self, url):
         raise UnsupportedError(url)
+
+
+_PLUGIN_OVERRIDES = collections.defaultdict(list)

yt_dlp/extractor/extractors.py

@@ -24,3 +24,5 @@
 
 globals().update(_PLUGIN_CLASSES)
 _ALL_CLASSES[:0] = _PLUGIN_CLASSES.values()
+
+from .common import _PLUGIN_OVERRIDES  # noqa: F401

yt_dlp/extractor/testurl.py

@@ -23,11 +23,12 @@ def _real_extract(self, url):
         if len(matching_extractors) == 0:
             raise ExtractorError(f'No extractors matching {extractor_id!r} found', expected=True)
         elif len(matching_extractors) > 1:
-            try:  # Check for exact match
+            extractor = next((  # Check for exact match
-                extractor = next(
+                ie for ie in matching_extractors if ie.IE_NAME.lower() == extractor_id.lower()
-                    ie for ie in matching_extractors
+            ), None) or next((  # Check for exact match without plugin suffix
-                    if ie.IE_NAME.lower() == extractor_id.lower())
+                ie for ie in matching_extractors if ie.IE_NAME.split('+')[0].lower() == extractor_id.lower()
-            except StopIteration:
+            ), None)
+            if not extractor:
                 raise ExtractorError(
                     'Found multiple matching extractors: %s' % ' '.join(ie.IE_NAME for ie in matching_extractors),
                     expected=True)