bwd compat for pipe.begin_training

spacy/errors.py

@@ -85,7 +85,9 @@ class Warnings:
             "attribute or operator.")
 
     # TODO: fix numbering after merging develop into master
-    W089 = ("The nlp.begin_training method has been renamed to nlp.initialize.")
+    W089 = ("The 'begin_training' method has been renamed to 'initialize', "
+            "for calls to 'nlp' as well as for the individual pipeline "
+            "components.")
     W090 = ("Could not locate any {format} files in path '{path}'.")
     W091 = ("Could not clean/remove the temp directory at {dir}: {msg}.")
     W092 = ("Ignoring annotations for sentence starts, as dependency heads are set.")

spacy/language.py

@@ -1207,7 +1207,11 @@ class Language:
             )
             self.tokenizer.initialize(get_examples, nlp=self, **tok_settings)
         for name, proc in self.pipeline:
-            if hasattr(proc, "initialize"):
+            # backwards compatibility for older components
+            if hasattr(proc, "begin_training"):
+                warnings.warn(Warnings.W089, DeprecationWarning)
+                proc.begin_training(get_examples, pipeline=self.pipeline, sgd=self._optimizer)
+            elif hasattr(proc, "initialize"):
                 p_settings = I["components"].get(name, {})
                 p_settings = validate_init_settings(
                     proc.initialize, p_settings, section="components", name=name