@classmethod<EOL><INDENT>def from_config(cls, name, config):<DEDENT>
installed_classes = cls.get_installed_classes()<EOL>if name not in installed_classes:<EOL><INDENT>raise ValueError("<STR_LIT>" % cls.__name__.lower())<EOL><DEDENT>pluggable_class = installed_classes[name]<EOL>pluggable_class.validate_config(config)<EOL>instance = pluggable_class()<EOL>if not instance.name:<EOL><INDENT>instance.name = name<EOL><DEDENT>instance.apply_config(config)<EOL>return instance<EOL>
Behaves like the base Configurable class's `from_config()` except this
makes sure that the `Pluggable` subclass with the given name is
actually a properly installed plugin first.