Start working with mypy

parso/cache.py

@@ -7,11 +7,7 @@ import shutil
 import platform
 import logging
 import warnings
-
-try:
-    import cPickle as pickle
-except:
-    import pickle
+import pickle
 
 from parso.file_io import FileIO
 

parso/normalizer.py

@@ -149,8 +149,8 @@ class Issue(object):
 
 
 class Rule(object):
-    code = None
-    message = None
+    code: int
+    message: str
 
     def __init__(self, normalizer):
         self._normalizer = normalizer

parso/tree.py

@@ -23,7 +23,7 @@ class NodeOrLeaf(object):
     The base class for nodes and leaves.
     """
     __slots__ = ()
-    type = None
+    type: str
     '''
     The type is a string that typically matches the types of the grammar file.
     '''
@@ -257,7 +257,6 @@ class BaseNode(NodeOrLeaf):
     A node has children, a type and possibly a parent node.
     """
     __slots__ = ('children', 'parent')
-    type = None
 
     def __init__(self, children):
         self.children = children

setup.cfg

@@ -10,3 +10,16 @@ ignore =
   E226,
   # line break before binary operator
   W503,
+
+
+[mypy]
+disallow_subclassing_any = True
+
+# Avoid creating future gotchas emerging from bad typing
+warn_redundant_casts = True
+warn_unused_ignores = True
+warn_return_any = True
+warn_unused_configs = True
+warn_unreachable = True
+
+strict_equality = True

setup.py

@@ -12,42 +12,47 @@ __AUTHOR_EMAIL__ = 'davidhalter88@gmail.com'
 
 readme = open('README.rst').read() + '\n\n' + open('CHANGELOG.rst').read()
 
-setup(name='parso',
-      version=parso.__version__,
-      description='A Python Parser',
-      author=__AUTHOR__,
-      author_email=__AUTHOR_EMAIL__,
-      include_package_data=True,
-      maintainer=__AUTHOR__,
-      maintainer_email=__AUTHOR_EMAIL__,
-      url='https://github.com/davidhalter/parso',
-      license='MIT',
-      keywords='python parser parsing',
-      long_description=readme,
-      packages=find_packages(exclude=['test']),
-      package_data={'parso': ['python/grammar*.txt', 'py.typed', '*.pyi', '**/*.pyi']},
-      platforms=['any'],
-      python_requires='>=3.6',
-      classifiers=[
-          'Development Status :: 4 - Beta',
-          'Environment :: Plugins',
-          'Intended Audience :: Developers',
-          'License :: OSI Approved :: MIT License',
-          'Operating System :: OS Independent',
-          'Programming Language :: Python :: 3',
-          'Programming Language :: Python :: 3.6',
-          'Programming Language :: Python :: 3.7',
-          'Programming Language :: Python :: 3.8',
-          'Programming Language :: Python :: 3.9',
-          'Topic :: Software Development :: Libraries :: Python Modules',
-          'Topic :: Text Editors :: Integrated Development Environments (IDE)',
-          'Topic :: Utilities',
-          'Typing :: Typed',
-      ],
-      extras_require={
-          'testing': [
-              'pytest<6.0.0',
-              'docopt',
-          ],
-      },
-      )
+setup(
+    name='parso',
+    version=parso.__version__,
+    description='A Python Parser',
+    author=__AUTHOR__,
+    author_email=__AUTHOR_EMAIL__,
+    include_package_data=True,
+    maintainer=__AUTHOR__,
+    maintainer_email=__AUTHOR_EMAIL__,
+    url='https://github.com/davidhalter/parso',
+    license='MIT',
+    keywords='python parser parsing',
+    long_description=readme,
+    packages=find_packages(exclude=['test']),
+    package_data={'parso': ['python/grammar*.txt', 'py.typed', '*.pyi', '**/*.pyi']},
+    platforms=['any'],
+    python_requires='>=3.6',
+    classifiers=[
+        'Development Status :: 4 - Beta',
+        'Environment :: Plugins',
+        'Intended Audience :: Developers',
+        'License :: OSI Approved :: MIT License',
+        'Operating System :: OS Independent',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
+        'Programming Language :: Python :: 3.8',
+        'Programming Language :: Python :: 3.9',
+        'Topic :: Software Development :: Libraries :: Python Modules',
+        'Topic :: Text Editors :: Integrated Development Environments (IDE)',
+        'Topic :: Utilities',
+        'Typing :: Typed',
+    ],
+    extras_require={
+        'testing': [
+            'pytest<6.0.0',
+            'docopt',
+        ],
+        'qa': [
+            'flake8==3.8.3',
+            'mypy==0.782',
+        ],
+    },
+)