Extract StaticModule and patch_path helpers.

setuptools/config.py

@@ -10,6 +10,7 @@ from collections import defaultdict
 from functools import partial
 from functools import wraps
 from importlib import import_module
+import contextlib
 
 from distutils.errors import DistutilsOptionError, DistutilsFileError
 from setuptools.extern.packaging.version import LegacyVersion, parse
@@ -20,6 +21,44 @@ from setuptools.extern.six import string_types, PY3
 __metaclass__ = type
 
 
+class StaticModule:
+    """
+    Attempt to load the module by the name
+    """
+    def __init__(self, name):
+        spec = importlib.util.find_spec(module_name)
+        with open(spec.origin) as strm:
+            src = strm.read()
+        module = ast.parse(src)
+        vars(self).update(locals())
+        del self.self
+
+    def __getattr__(self, attr):
+        try:
+            return next(
+                ast.literal_eval(statement.value)
+                for statement in self.module.body
+                if isinstance(statement, ast.Assign)
+                for target in statement.targets
+                if isinstance(target, ast.Name) and target.id == attr
+            )
+        except Exception:
+            raise AttributeError(
+                "{self.name} has no attribute {attr}".format(**locals()))
+
+
+@contextlib.contextmanager
+def patch_path(path):
+    """
+    Add path to front of sys.path for the duration of the context.
+    """
+    try:
+        sys.path.insert(0, path)
+        yield
+    finally:
+        sys.path.remove(path)
+
+
 def read_configuration(
         filepath, find_others=False, ignore_option_errors=False):
     """Read given configuration file and returns options from it as a dict.
@@ -346,50 +385,15 @@ class ConfigHandler:
                 # A custom parent directory was specified for all root modules
                 parent_path = os.path.join(os.getcwd(), package_dir[''])
 
-        fpath = os.path.join(parent_path, *module_name.split('.'))
-        if os.path.exists(fpath + '.py'):
-            fpath += '.py'
-        elif os.path.isdir(fpath):
-            fpath = os.path.join(fpath, '__init__.py')
-        else:
-            raise DistutilsOptionError('Could not find module ' + module_name)
-        with open(fpath, 'rb') as fp:
-            src = fp.read()
-        found = False
-        top_level = ast.parse(src)
-        for statement in top_level.body:
-            if isinstance(statement, ast.Assign):
-                for target in statement.targets:
-                    if isinstance(target, ast.Name) \
-                            and target.id == attr_name:
-                        try:
-                            value = ast.literal_eval(statement.value)
-                        except ValueError:
-                            found = False
-                        else:
-                            found = True
-                    elif isinstance(target, ast.Tuple) \
-                        and any(isinstance(t, ast.Name) and t.id == attr_name
-                                for t in target.elts):
-                        try:
-                            stmnt_value = ast.literal_eval(statement.value)
-                        except ValueError:
-                            found = False
-                        else:
-                            for t, v in zip(target.elts, stmnt_value):
-                                if isinstance(t, ast.Name) \
-                                        and t.id == attr_name:
-                                    value = v
-                                    found = True
-        if not found:
-            # Fall back to extracting attribute via importing
-            sys.path.insert(0, parent_path)
+        with patch_path(parent_path):
             try:
+                # attempt to load value statically
+                return getattr(StaticModule(module_name), attr_name)
+            except Exception:
+                # fallback to simple import
                 module = import_module(module_name)
-                value = getattr(module, attr_name)
-            finally:
-                sys.path = sys.path[1:]
-        return value
+
+        return getattr(module, attr_name)
 
     @classmethod
     def _get_parser_compound(cls, *parse_methods):

setuptools/tests/test_config.py

@@ -103,7 +103,7 @@ class TestConfigurationReader:
             'version = attr: none.VERSION\n'
             'keywords = one, two\n'
         )
-        with pytest.raises(DistutilsOptionError):
+        with pytest.raises(ImportError):
             read_configuration('%s' % config)
 
         config_dict = read_configuration(