Merge commit 'd6bcf5e8' into feature/2093-docs-revamp

changelog.d/1753.change.rst

+``attr:`` now extracts variables through rudimentary examination of the AST,
+thereby supporting modules with third-party imports.  If examining the AST
+fails to find the variable, ``attr:`` falls back to the old behavior of
+importing the module.

docs/userguide/declarative_config.txt

@@ -92,7 +92,7 @@ Metadata and options are set in the config sections of the same name.
 * In some cases, complex values can be provided in dedicated subsections for
   clarity.
 
-* Some keys allow ``file:``, ``attr:``, and ``find:`` and ``find_namespace:`` directives in
+* Some keys allow ``file:``, ``attr:``, ``find:``, and ``find_namespace:`` directives in
   order to cover common usecases.
 
 * Unknown keys are ignored.
@@ -146,6 +146,12 @@ Special directives:
 
 * ``attr:`` - Value is read from a module attribute.  ``attr:`` supports
   callables and iterables; unsupported types are cast using ``str()``.
+
+  In order to support the common case of a literal value assigned to a variable
+  in a module containing (directly or indirectly) third-party imports,
+  ``attr:`` first tries to read the value from the module by examining the
+  module's AST.  If that fails, ``attr:`` falls back to importing the module.
+
 * ``file:`` - Value is read from a list of files and then concatenated
 
 
@@ -237,4 +243,4 @@ data_files               dict                                 40.6.0
 
 Notes:
 1. In the `package_data` section, a key named with a single asterisk (`*`)
-refers to all packages, in lieu of the empty string used in `setup.py`.
\ No newline at end of file
+refers to all packages, in lieu of the empty string used in `setup.py`.

setuptools/config.py

 from __future__ import absolute_import, unicode_literals
+import ast
 import io
 import os
 import sys
@@ -344,14 +345,50 @@ class ConfigHandler:
             elif '' in package_dir:
                 # A custom parent directory was specified for all root modules
                 parent_path = os.path.join(os.getcwd(), package_dir[''])
-        sys.path.insert(0, parent_path)
-        try:
-            module = import_module(module_name)
-            value = getattr(module, attr_name)
-
-        finally:
-            sys.path = sys.path[1:]
 
+        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)
+            try:
+                module = import_module(module_name)
+                value = getattr(module, attr_name)
+            finally:
+                sys.path = sys.path[1:]
         return value
 
     @classmethod

setuptools/tests/test_config.py

@@ -103,7 +103,7 @@ class TestConfigurationReader:
             'version = attr: none.VERSION\n'
             'keywords = one, two\n'
         )
-        with pytest.raises(ImportError):
+        with pytest.raises(DistutilsOptionError):
             read_configuration('%s' % config)
 
         config_dict = read_configuration(
@@ -300,6 +300,18 @@ class TestMetadata:
         with get_dist(tmpdir) as dist:
             assert dist.metadata.version == '2016.11.26'
 
+        subpack.join('submodule.py').write(
+            'import third_party_module\n'
+            'VERSION = (2016, 11, 26)'
+        )
+
+        config.write(
+            '[metadata]\n'
+            'version = attr: fake_package.subpackage.submodule.VERSION\n'
+        )
+        with get_dist(tmpdir) as dist:
+            assert dist.metadata.version == '2016.11.26'
+
     def test_version_file(self, tmpdir):
 
         _, config = fake_env(