Merge pull request #17 from dstufft/setup-py

Port the setup.py from pyca/cryptography to bcrypt

setup.py

@@ -1,11 +1,13 @@
 #!/usr/bin/env python
-import os
 import sys
+from distutils.command.build import build
 
 from setuptools import setup
+from setuptools.command.install import install
 from setuptools.command.test import test
 
 
+CFFI_DEPENDENCY = "cffi>=0.8"
 SIX_DEPENDENCY = "six>=1.4.1"
 
 
@@ -22,24 +24,42 @@ class _AttrDict(dict):
         self[key] = value
 
 
-# This is really hacky, but it ensures that if setup_requires are being used
-#   setup.py can import them. No idea why this is required.
-sys.path += [x for x in os.listdir(".") if x.endswith(".egg")]
+# Manually extract the __about__
+__about__ = _AttrDict()
+with open("bcrypt/__about__.py") as fp:
+    exec(fp.read(), __about__)
 
 
-try:
-    from bcrypt import __about__, _ffi
-except ImportError:
-    # installing - there is no cffi yet
-    ext_modules = []
+def get_ext_modules():
+    from bcrypt import _ffi
+    return [_ffi.verifier.get_extension()]
 
-    # Manually extract the __about__
-    __about__ = _AttrDict()
-    with open("bcrypt/__about__.py") as fp:
-        exec(fp.read(), __about__)
-else:
-    # building bdist - cffi is here!
-    ext_modules = [_ffi.verifier.get_extension()]
+
+class CFFIBuild(build):
+    """
+    This class exists, instead of just providing ``ext_modules=[...]`` directly
+    in ``setup()`` because importing cryptography requires we have several
+    packages installed first.
+
+    By doing the imports here we ensure that packages listed in
+    ``setup_requires`` are already installed.
+    """
+
+    def finalize_options(self):
+        self.distribution.ext_modules = get_ext_modules()
+        build.finalize_options(self)
+
+
+class CFFIInstall(install):
+    """
+    As a consequence of CFFIBuild and it's late addition of ext_modules, we
+    need the equivalent for the ``install`` command to install into platlib
+    install-dir rather than purelib.
+    """
+
+    def finalize_options(self):
+        self.distribution.ext_modules = get_ext_modules()
+        install.finalize_options(self)
 
 
 class PyTest(test):
@@ -54,6 +74,151 @@ class PyTest(test):
         sys.exit(errno)
 
 
+def keywords_with_side_effects(argv):
+    """
+    Get a dictionary with setup keywords that (can) have side effects.
+
+    :param argv: A list of strings with command line arguments.
+    :returns: A dictionary with keyword arguments for the ``setup()`` function.
+
+    This setup.py script uses the setuptools 'setup_requires' feature because
+    this is required by the cffi package to compile extension modules. The
+    purpose of ``keywords_with_side_effects()`` is to avoid triggering the cffi
+    build process as a result of setup.py invocations that don't need the cffi
+    module to be built (setup.py serves the dual purpose of exposing package
+    metadata).
+
+    All of the options listed by ``python setup.py --help`` that print
+    information should be recognized here. The commands ``clean``,
+    ``egg_info``, ``register``, ``sdist`` and ``upload`` are also recognized.
+    Any combination of these options and commands is also supported.
+
+    This function was originally based on the `setup.py script`_ of SciPy (see
+    also the discussion in `pip issue #25`_).
+
+    .. _pip issue #25: https://github.com/pypa/pip/issues/25
+    .. _setup.py script: https://github.com/scipy/scipy/blob/master/setup.py
+    """
+    no_setup_requires_arguments = (
+        '-h', '--help',
+        '-n', '--dry-run',
+        '-q', '--quiet',
+        '-v', '--verbose',
+        '-V', '--version',
+        '--author',
+        '--author-email',
+        '--classifiers',
+        '--contact',
+        '--contact-email',
+        '--description',
+        '--egg-base',
+        '--fullname',
+        '--help-commands',
+        '--keywords',
+        '--licence',
+        '--license',
+        '--long-description',
+        '--maintainer',
+        '--maintainer-email',
+        '--name',
+        '--no-user-cfg',
+        '--obsoletes',
+        '--platforms',
+        '--provides',
+        '--requires',
+        '--url',
+        'clean',
+        'egg_info',
+        'register',
+        'sdist',
+        'upload',
+    )
+
+    def is_short_option(argument):
+        """Check whether a command line argument is a short option."""
+        return len(argument) >= 2 and argument[0] == '-' and argument[1] != '-'
+
+    def expand_short_options(argument):
+        """Expand combined short options into canonical short options."""
+        return ('-' + char for char in argument[1:])
+
+    def argument_without_setup_requirements(argv, i):
+        """Check whether a command line argument needs setup requirements."""
+        if argv[i] in no_setup_requires_arguments:
+            # Simple case: An argument which is either an option or a command
+            # which doesn't need setup requirements.
+            return True
+        elif (is_short_option(argv[i]) and
+              all(option in no_setup_requires_arguments
+                  for option in expand_short_options(argv[i]))):
+            # Not so simple case: Combined short options none of which need
+            # setup requirements.
+            return True
+        elif argv[i - 1:i] == ['--egg-base']:
+            # Tricky case: --egg-info takes an argument which should not make
+            # us use setup_requires (defeating the purpose of this code).
+            return True
+        else:
+            return False
+
+    if all(argument_without_setup_requirements(argv, i)
+           for i in range(1, len(argv))):
+        return {
+            "cmdclass": {
+                "build": DummyCFFIBuild,
+                "install": DummyCFFIInstall,
+                "test": DummyPyTest,
+            }
+        }
+    else:
+        return {
+            "setup_requires": [CFFI_DEPENDENCY, SIX_DEPENDENCY],
+            "cmdclass": {
+                "build": CFFIBuild,
+                "install": CFFIInstall,
+                "test": PyTest,
+            }
+        }
+
+
+setup_requires_error = ("Requested setup command that needs 'setup_requires' "
+                        "while command line arguments implied a side effect "
+                        "free command or option.")
+
+
+class DummyCFFIBuild(build):
+    """
+    This class makes it very obvious when ``keywords_with_side_effects()`` has
+    incorrectly interpreted the command line arguments to ``setup.py build`` as
+    one of the 'side effect free' commands or options.
+    """
+
+    def run(self):
+        raise RuntimeError(setup_requires_error)
+
+
+class DummyCFFIInstall(install):
+    """
+    This class makes it very obvious when ``keywords_with_side_effects()`` has
+    incorrectly interpreted the command line arguments to ``setup.py install``
+    as one of the 'side effect free' commands or options.
+    """
+
+    def run(self):
+        raise RuntimeError(setup_requires_error)
+
+
+class DummyPyTest(test):
+    """
+    This class makes it very obvious when ``keywords_with_side_effects()`` has
+    incorrectly interpreted the command line arguments to ``setup.py test`` as
+    one of the 'side effect free' commands or options.
+    """
+
+    def run_tests(self):
+        raise RuntimeError(setup_requires_error)
+
+
 setup(
     name=__about__.__title__,
     version=__about__.__version__,
@@ -66,12 +231,8 @@ setup(
     author=__about__.__author__,
     author_email=__about__.__email__,
 
-    setup_requires=[
-        "cffi",
-        SIX_DEPENDENCY,
-    ],
     install_requires=[
-        "cffi",
+        CFFI_DEPENDENCY,
         SIX_DEPENDENCY,
     ],
     extras_require={
@@ -93,10 +254,7 @@ setup(
         "bcrypt": ["crypt_blowfish-1.2/*"],
     },
 
-    ext_modules=ext_modules,
-
     zip_safe=False,
-    cmdclass={"test": PyTest},
 
     classifiers=[
         "Programming Language :: Python :: Implementation :: CPython",
@@ -107,5 +265,7 @@ setup(
         "Programming Language :: Python :: 3",
         "Programming Language :: Python :: 3.2",
         "Programming Language :: Python :: 3.3",
-    ]
+    ],
+
+    **keywords_with_side_effects(sys.argv)
 )