Typing support

.gitignore

@@ -29,3 +29,5 @@ tmp-KafkaCluster
 .venv
 venv_test
 venv_examples
+.vscode/
+.dmypy.json

.travis.yml

@@ -65,8 +65,10 @@ install:
 script:
  - flake8
  # Build package
- -  pip install --global-option=build_ext --global-option="-Itmp-build/include/" --global-option="-Ltmp-build/lib" . .[avro] .[schema-registry] .[json] .[protobuf]
+ - pip install --global-option=build_ext --global-option="-Itmp-build/include/" --global-option="-Ltmp-build/lib" . .[avro] .[schema-registry] .[json] .[protobuf]
  - ldd staging/libs/* || otool -L staging/libs/* || true
+ # Run type checks
+ - mypy src/confluent_kafka
  # Run tests
  - if [[ $TRAVIS_OS_NAME == "linux" ]]; then LD_LIBRARY_PATH=$LD_LIBRARY_PATH:staging/libs DYLD_LIBRARY_PATH=$DYLD_LIBRARY_PATH:staging/libs python -m pytest --timeout 600 --ignore=tmp-build || travis_terminate 1; fi
  # Build docs

mypy.ini

@@ -0,0 +1,6 @@
+[mypy]
+show_error_codes=true
+disallow_untyped_defs=true
+disallow_untyped_calls=true
+warn_redundant_casts=true
+strict_optional=true

setup.py

@@ -12,13 +12,20 @@
 INSTALL_REQUIRES = [
     'futures;python_version<"3.2"',
     'enum34;python_version<"3.4"',
+    'six'
 ]
 
 TEST_REQUIRES = [
     'pytest==4.6.4;python_version<"3.0"',
     'pytest;python_version>="3.0"',
     'pytest-timeout',
-    'flake8'
+    'flake8',
+    # Cap the version to avoid issues with newer editions. Should be periodically updated!
+    'mypy<=0.991',
+    'types-protobuf',
+    'types-jsonschema',
+    'types-requests',
+    'types-six'
 ]
 
 DOC_REQUIRES = ['sphinx', 'sphinx-rtd-theme']
@@ -81,6 +88,7 @@ def get_install_requirements(path):
       author_email='[email protected]',
       url='https://github.com/confluentinc/confluent-kafka-python',
       ext_modules=[module],
+      package_data={"confluent_kafka": ["py.typed"]},
       packages=find_packages('src'),
       package_dir={'': 'src'},
       data_files=[('', [os.path.join(work_dir, 'LICENSE.txt')])],

src/confluent_kafka/__init__.py

@@ -60,19 +60,19 @@ class ThrottleEvent(object):
     :ivar float throttle_time: The amount of time (in seconds) the broker throttled (delayed) the request
     """
 
-    def __init__(self, broker_name,
-                 broker_id,
-                 throttle_time):
+    def __init__(self, broker_name: str,
+                 broker_id: int,
+                 throttle_time: float):
         self.broker_name = broker_name
         self.broker_id = broker_id
         self.throttle_time = throttle_time
 
-    def __str__(self):
+    def __str__(self) -> str:
         return "{}/{} throttled for {} ms".format(self.broker_name, self.broker_id,
                                                   int(self.throttle_time * 1000))
 
 
-def _resolve_plugins(plugins):
+def _resolve_plugins(plugins: str) -> str:
     """ Resolve embedded plugins from the wheel's library directory.
 
         For internal module use only.