OMG we're running a hook

pre_commit/languages/python.py

@@ -0,0 +1,32 @@
+
+import contextlib
+from plumbum import local
+from plumbum.machines.session import ShellSession
+
+PY_ENV = 'py_env'
+
+
+@contextlib.contextmanager
+def in_env():
+    with ShellSession(local['bash'].popen()) as env:
+        env.run('source {0}/bin/activate'.format(PY_ENV))
+        yield env
+
+
+def install_environment():
+    assert local.path('setup.py').exists()
+    # Install a virtualenv
+    local['virtualenv'][PY_ENV]()
+
+    with in_env() as env:
+        # Run their setup.py
+        env.run('pip install .')
+
+
+def run_hook(hook, file_args):
+    with in_env() as env:
+        # TODO: batch filenames
+        return env.run(
+            ' '.join([hook['entry']] + hook.get('args', []) + list(file_args)),
+            retcode=None,
+        )