PR: Support mypy

MANIFEST.in

@@ -3,3 +3,4 @@ include CHANGELOG.md
 include LICENSE.txt
 include README.md
 recursive-include qtpy/tests *.py *.ui
+include qtpy/py.typed

README.md

@@ -71,6 +71,25 @@ conda install qtpy
 ```
 
 
+### mypy
+
+A CLI is offered to help with usage of QtPy.  Presently, the only feature
+is to generate command line arguments for Mypy that will enable it to
+process the QtPy source files with the same API as QtPy itself would have
+selected.
+
+```
+--always-false=PYQT4 --always-false=PYQT5 --always-false=PYSIDE --always-true=PYSIDE2
+```
+
+If using bash or similar, this can be integrated into the Mypy command line
+as follows.
+
+```console
+$ env/bin/mypy --package mypackage $(env/bin/qtpy mypy-args)
+```
+
+
 ## Contributing
 
 Everyone is welcome to contribute!

qtpy/__init__.py

@@ -220,8 +220,10 @@ class PythonQtWarning(Warning):
     warnings.warn('Selected binding "{}" could not be found, '
                   'using "{}"'.format(initial_api, API), RuntimeWarning)
 
-API_NAME = {'pyqt5': 'PyQt5', 'pyqt': 'PyQt4', 'pyqt4': 'PyQt4',
-            'pyside': 'PySide', 'pyside2':'PySide2'}[API]
+API_NAMES = {'pyqt5': 'PyQt5', 'pyqt': 'PyQt4', 'pyqt4': 'PyQt4',
+            'pyside': 'PySide', 'pyside2':'PySide2'}
+APIS = sorted(name.upper() for name in set(API_NAMES.values()))
+API_NAME = API_NAMES[API]
 
 if PYQT4:
     import sip

qtpy/__main__.py

@@ -0,0 +1,9 @@
+import qtpy.cli
+
+
+def main():
+    return qtpy.cli.cli()
+
+
+if __name__ == "__main__":
+    main()

qtpy/cli.py

@@ -0,0 +1,77 @@
+# -*- coding: utf-8 -*-
+# -----------------------------------------------------------------------------
+# Copyright © 2009- The QtPy Contributors
+#
+# Released under the terms of the MIT License
+# (see LICENSE.txt for details)
+# -----------------------------------------------------------------------------
+
+"""Provide a CLI to allow configuring developer settings, including mypy."""
+
+# Standard library imports
+import argparse
+import sys
+import textwrap
+
+
+class RawDescriptionArgumentDefaultsHelpFormatter(
+    argparse.RawDescriptionHelpFormatter,
+    argparse.ArgumentDefaultsHelpFormatter,
+):
+    pass
+
+
+def cli(args=sys.argv[1:]):
+    parser = argparse.ArgumentParser(
+        description="Features in support of development with QtPy.",
+        formatter_class=RawDescriptionArgumentDefaultsHelpFormatter,
+    )
+
+    parser.set_defaults(func=parser.print_help)
+
+    cli_subparsers = parser.add_subparsers()
+
+    mypy_args_parser = cli_subparsers.add_parser(
+        name='mypy-args',
+        description=textwrap.dedent(
+            """\
+            Generate command line arguments for using mypy with QtPy.
+
+            This will generate strings similar to the following which help guide mypy
+            through which library QtPy would have used so that mypy can get the proper
+            underlying type hints.
+
+                --always-false=PYQT4 --always-false=PYQT5 --always-false=PYSIDE --always-true=PYSIDE2
+
+            Use such as:
+
+                env/bin/mypy --package mypackage $(env/bin/qtpy mypy-args)
+            """
+        ),
+        formatter_class=RawDescriptionArgumentDefaultsHelpFormatter,
+    )
+    mypy_args_parser.set_defaults(func=mypy_args)
+
+    arguments = parser.parse_args(args=args)
+
+    reserved_parameters = {'func'}
+    cleaned = {
+        k: v
+        for k, v in vars(arguments).items()
+        if k not in reserved_parameters
+    }
+
+    arguments.func(**cleaned)
+
+
+def mypy_args():
+    options = {False: '--always-false', True: '--always-true'}
+
+    import qtpy
+
+    apis_active = {name: qtpy.API.lower() == name.lower() for name in qtpy.APIS}
+    print(' '.join(
+        f'{options[is_active]}={name.upper()}'
+        for name, is_active
+        in apis_active.items()
+    ))

qtpy/tests/test_cli.py

@@ -0,0 +1,45 @@
+from __future__ import absolute_import
+
+import subprocess
+import sys
+
+import pytest
+
+import qtpy
+
+
+subcommands = [
+    ['mypy'],
+    ['mypy', 'args'],
+]
+
+
+@pytest.mark.parametrize(
+    argnames=['subcommand'],
+    argvalues=[[subcommand] for subcommand in subcommands],
+    ids=[' '.join(subcommand) for subcommand in subcommands],
+)
+def test_cli_help_does_not_fail(subcommand):
+    # .check_call() over .run(..., check=True) because of py2
+    subprocess.check_call(
+        [sys.executable, '-m', 'qtpy', *subcommand, '--help'],
+    )
+
+
+def test_cli_mypy_args():
+    output = subprocess.check_output(
+        [sys.executable, '-m', 'qtpy', 'mypy', 'args'],
+    )
+
+    if qtpy.PYQT4:
+        expected = b'--always-true=PYQT4 --always-false=PYQT5 --always-false=PYSIDE --always-false=PYSIDE2\n'
+    elif qtpy.PYQT5:
+        expected = b'--always-false=PYQT4 --always-true=PYQT5 --always-false=PYSIDE --always-false=PYSIDE2\n'
+    elif qtpy.PYSIDE:
+        expected = b'--always-false=PYQT4 --always-false=PYQT5 --always-true=PYSIDE --always-false=PYSIDE2\n'
+    elif qtpy.PYSIDE2:
+        expected = b'--always-false=PYQT4 --always-false=PYQT5 --always-false=PYSIDE --always-true=PYSIDE2\n'
+    else:
+        assert False, 'No valid API to test'
+
+    assert output == expected

setup.py

@@ -47,5 +47,7 @@
         'Programming Language :: Python :: 3',
         'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
-        'Programming Language :: Python :: 3.5']
+        'Programming Language :: Python :: 3.5'],
+    entry_points={'console_scripts': 'qtpy = qtpy.__main__:main [cli]'},
+    include_package_data=True
 )