Implement a "literal_attr:" config directive

2 files changed, 117 insertions, 9 deletions

diff --git a/setuptools/config.py b/setuptools/config.py
index 9b9a0c45..d1456cac 100644
--- a/setuptools/config.py
+++ b/setuptools/config.py
@@ -1,4 +1,5 @@
 from __future__ import absolute_import, unicode_literals
+import ast
 import io
 import os
 import sys
@@ -316,15 +317,22 @@ class ConfigHandler:
         Examples:
             attr: package.attr
             attr: package.module.attr
+            literal_attr: package.attr
+            literal_attr: package.module.attr
 
         :param str value:
         :rtype: str
         """
         attr_directive = 'attr:'
-        if not value.startswith(attr_directive):
+        literal_attr_directive = 'literal_attr:'
+        if value.startswith(attr_directive):
+            directive = attr_directive
+        elif value.startswith(literal_attr_directive):
+            directive = literal_attr_directive
+        else:
             return value
 
-        attrs_path = value.replace(attr_directive, '').strip().split('.')
+        attrs_path = value.replace(directive, '').strip().split('.')
         attr_name = attrs_path.pop()
 
         module_name = '.'.join(attrs_path)
@@ -344,13 +352,49 @@ 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:]
+        if directive == attr_directive:
+            sys.path.insert(0, parent_path)
+            try:
+                module = import_module(module_name)
+                value = getattr(module, attr_name)
+            finally:
+                sys.path = sys.path[1:]
+
+        elif directive == literal_attr_directive:
+            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:
+                            value = ast.literal_eval(statement.value)
+                            found = True
+                        elif isinstance(target, ast.Tuple) \
+                            and any(isinstance(t, ast.Name) and t.id==attr_name
+                                    for t in target.elts):
+                                stmnt_value = ast.literal_eval(statement.value)
+                                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:
+                raise DistutilsOptionError(
+                    'No literal assignment to {!r} found in file'
+                    .format(attr_name)
+                )
 
         return value
 
diff --git a/setuptools/tests/test_config.py b/setuptools/tests/test_config.py
index 2fa0b374..03e6916b 100644
--- a/setuptools/tests/test_config.py
+++ b/setuptools/tests/test_config.py
@@ -300,6 +300,37 @@ class TestMetadata:
         with get_dist(tmpdir) as dist:
             assert dist.metadata.version == '2016.11.26'
 
+    def test_literal_version(self, tmpdir):
+
+        _, config = fake_env(
+            tmpdir,
+            '[metadata]\n'
+            'version = literal_attr: fake_package.VERSION\n'
+        )
+        with get_dist(tmpdir) as dist:
+            assert dist.metadata.version == '1.2.3'
+
+        config.write(
+            '[metadata]\n'
+            'version = literal_attr: fake_package.VERSION_MAJOR\n'
+        )
+        with get_dist(tmpdir) as dist:
+            assert dist.metadata.version == '1'
+
+        subpack = tmpdir.join('fake_package').mkdir('subpackage')
+        subpack.join('__init__.py').write('')
+        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(
@@ -332,6 +363,17 @@ class TestMetadata:
         with get_dist(tmpdir) as dist:
             assert dist.metadata.version == '1.2.3'
 
+        config.write(
+            '[metadata]\n'
+            'version = literal_attr: fake_package_simple.VERSION\n'
+            '[options]\n'
+            'package_dir =\n'
+            '    = src\n'
+        )
+
+        with get_dist(tmpdir) as dist:
+            assert dist.metadata.version == '1.2.3'
+
     def test_version_with_package_dir_rename(self, tmpdir):
 
         _, config = fake_env(
@@ -347,6 +389,17 @@ class TestMetadata:
         with get_dist(tmpdir) as dist:
             assert dist.metadata.version == '1.2.3'
 
+        config.write(
+            '[metadata]\n'
+            'version = literal_attr: fake_package_rename.VERSION\n'
+            '[options]\n'
+            'package_dir =\n'
+            '    fake_package_rename = fake_dir\n'
+        )
+
+        with get_dist(tmpdir) as dist:
+            assert dist.metadata.version == '1.2.3'
+
     def test_version_with_package_dir_complex(self, tmpdir):
 
         _, config = fake_env(
@@ -362,6 +415,17 @@ class TestMetadata:
         with get_dist(tmpdir) as dist:
             assert dist.metadata.version == '1.2.3'
 
+        config.write(
+            '[metadata]\n'
+            'version = literal_attr: fake_package_complex.VERSION\n'
+            '[options]\n'
+            'package_dir =\n'
+            '    fake_package_complex = src/fake_dir\n'
+        )
+
+        with get_dist(tmpdir) as dist:
+            assert dist.metadata.version == '1.2.3'
+
     def test_unknown_meta_item(self, tmpdir):
 
         fake_env(