Implement declarative config for compatibility with setuptools declarative config

setup.py

@@ -68,6 +68,9 @@ def parse(root):
         [setuptools.file_finders]
         setuptools_scm = setuptools_scm.integration:find_files
 
+        [setuptools.finalize_distribution_options]
+        setuptools_scm = setuptools_scm.integration:infer_version
+
         [setuptools_scm.parse_scm]
         .hg = setuptools_scm.hg:parse
         .git = setuptools_scm.git:parse
@@ -111,6 +114,7 @@ def parse(root):
         "Topic :: Utilities",
     ],
     python_requires=">=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*",
+    extras_require=dict(toml=["toml"]),
 )
 
 if __name__ == "__main__":

src/setuptools_scm/__init__.py

@@ -80,6 +80,9 @@ def dump_version(root, version, write_to, template=None):
 
 
 def _do_parse(config):
+    if not config.enabled:
+        return
+
     pretended = os.environ.get(PRETEND_KEY)
     if pretended:
         # we use meta here since the pretended version
@@ -146,18 +149,24 @@ def get_version(
     config.fallback_version = fallback_version
     config.parse = parse
     config.git_describe_command = git_describe_command
+    config.enabled = True
+    return _get_version(config)
+
 
+def _get_version(config):
     parsed_version = _do_parse(config)
 
     if parsed_version:
         version_string = format_version(
-            parsed_version, version_scheme=version_scheme, local_scheme=local_scheme
+            parsed_version,
+            version_scheme=config.version_scheme,
+            local_scheme=config.local_scheme,
         )
         dump_version(
-            root=root,
+            root=config.root,
             version=version_string,
-            write_to=write_to,
-            template=write_to_template,
+            write_to=config.write_to,
+            template=config.write_to_template,
         )
 
         return version_string

src/setuptools_scm/config.py

@@ -49,6 +49,7 @@ class Configuration(object):
     parse = None
     _tag_regex = None
     _absolute_root = None
+    enabled = False
 
     def __init__(self, relative_to=None, root="."):
         # TODO:
@@ -105,3 +106,16 @@ def tag_regex(self):
     @tag_regex.setter
     def tag_regex(self, value):
         self._tag_regex = _check_tag_regex(value)
+
+    @classmethod
+    def from_file(cls, name="pyproject.toml"):
+        """
+        Read Configuration from pyproject.toml (or similar)
+        """
+        if not os.path.isfile(name):
+            return cls()
+        with open(name) as strm:
+            defn = __import__("toml").load(strm)
+        config = cls()
+        vars(config).update(defn.get("tool", {}).get("setuptools_scm", {}))
+        return config

src/setuptools_scm/integration.py

@@ -1,8 +1,9 @@
 from pkg_resources import iter_entry_points
 
 from .version import _warn_if_setuptools_outdated
+from .config import Configuration
 from .utils import do
-from . import get_version
+from . import get_version, _get_version
 
 
 def version_keyword(dist, keyword, value):
@@ -28,3 +29,9 @@ def find_files(path=""):
         if res:
             return res
     return []
+
+
+def infer_version(dist):
+    version = _get_version(Configuration.from_file())
+    if version:
+        dist.metadata.version = version

testing/test_config.py

@@ -1,3 +1,5 @@
+from __future__ import unicode_literals
+
 from setuptools_scm.config import Configuration
 
 import pytest
@@ -18,3 +20,10 @@ def test_tag_regex(tag, expected_version):
     match = config.tag_regex.match(tag)
     version = match.group("version")
     assert version == expected_version
+
+
+def test_config_from_pyproject(tmpdir):
+    fn = tmpdir / "pyproject.toml"
+    fn.write_text("[tool.setuptools_scm]\nenabled = true\n", encoding="utf-8")
+    config = Configuration.from_file(str(fn))
+    assert config.enabled

testing/test_integration.py

@@ -0,0 +1,17 @@
+import sys
+
+from setuptools_scm.utils import do
+
+
+def test_pyproject_support(tmpdir, monkeypatch):
+    monkeypatch.delenv("SETUPTOOLS_SCM_DEBUG")
+    pkg = tmpdir.ensure("package", dir=42)
+    pkg.join("pyproject.toml").write(
+        """[tool.setuptools_scm]
+enabled = true
+fallback_version = "12.34"
+"""
+    )
+    pkg.join("setup.py").write("__import__('setuptools').setup()")
+    res = do((sys.executable, "setup.py", "--version"), pkg)
+    assert res == "12.34"

tox.ini

@@ -25,9 +25,12 @@ skip_install=
     test: False
 deps=
     pytest
+    setuptools >= 42
 commands=
     test: py.test []
     selfcheck: python setup.py --version
+extras =
+    toml
 
 [testenv:flake8]
 skip_install=True