Support pipeline factories via entry points (#2348)

spacy/errors.py

@@ -46,6 +46,8 @@ class Warnings(object):
             "use context-sensitive tensors. You can always add your own word "
             "vectors, or use one of the larger models instead if available.")
     W008 = ("Evaluating {obj}.similarity based on empty vectors.")
+    W009 = ("Custom factory '{name}' provided by entry points of another "
+            "package overwrites built-in factory.")
 
 
 @add_codes

spacy/language.py

@@ -28,7 +28,7 @@ from .lang.punctuation import TOKENIZER_INFIXES
 from .lang.tokenizer_exceptions import TOKEN_MATCH
 from .lang.tag_map import TAG_MAP
 from .lang.lex_attrs import LEX_ATTRS, is_stop
-from .errors import Errors
+from .errors import Errors, Warnings, user_warning
 from . import util
 from . import about
 
@@ -139,6 +139,11 @@ class Language(object):
             100,000 characters in one text.
         RETURNS (Language): The newly constructed object.
         """
+        user_factories = util.get_entry_points('spacy_factories')
+        for factory in user_factories.keys():
+            if factory in self.factories:
+                user_warning(Warnings.W009.format(name=factory))
+        self.factories.update(user_factories)
         self._meta = dict(meta)
         self._path = None
         if vocab is True:

spacy/util.py

@@ -220,6 +220,19 @@ def get_package_path(name):
     return Path(pkg.__file__).parent
 
 
+def get_entry_points(key):
+    """Get registered entry points from other packages for a given key, e.g.
+    'spacy_factories' and return them as a dictionary, keyed by name.
+
+    key (unicode): Entry point name.
+    RETURNS (dict): Entry points, keyed by name.
+    """
+    result = {}
+    for entry_point in pkg_resources.iter_entry_points(key):
+        result[entry_point.name] = entry_point.load()
+    return result
+
+
 def is_in_jupyter():
     """Check if user is running spaCy from a Jupyter notebook by detecting the
     IPython kernel. Mainly used for the displaCy visualizer.