Add new initialize hookspec to make suppress plugins easier

src/ocrmypdf/_plugin_manager.py

@@ -116,6 +116,9 @@ def get_parser_options_plugins(
     plugin_manager = get_plugin_manager(pre_options.plugins)
 
     parser = get_parser()
+    plugin_manager.hook.initialize(  # pylint: disable=no-member
+        plugin_manager=plugin_manager
+    )
     plugin_manager.hook.add_options(parser=parser)  # pylint: disable=no-member
 
     options = parser.parse_args(args=args)

src/ocrmypdf/pluginspec.py

@@ -51,6 +51,33 @@ def get_logging_console() -> Handler:
     """
 
 
+@hookspec
+def initialize(plugin_manager: pluggy.PluginManager):
+    """Called when this plugin is first loaded into OCRmyPDF.
+
+    The primary intended use of this is for plugins to check compatibility with other
+    plugins and possibly block other blocks, a plugin that wishes to block ocrmypdf's
+    built-in optimize plugin could do:
+
+    .. code-block::
+
+        plugin_manager.set_blocked('ocrmypdf.builtin_plugins.optimize')
+
+    It would also be reasonable for an plugin implementation to check if it is unable
+    to proceed, for example, because a required dependency is missing. (If the plugin's
+    ability to proceed depends on options and arguments, use ``validate`` instead.)
+
+    Raises:
+        ocrmypdf.exceptions.ExitCodeException: If options are not acceptable
+            and the application should terminate gracefully with an informative
+            message and error code.
+
+    Note:
+        This hook will be called from the main process, and may modify global state
+        before child worker processes are forked.
+    """
+
+
 @hookspec
 def add_options(parser: ArgumentParser) -> None:
     """Allows the plugin to add its own command line and API arguments.