Drafted an implementation of a 'build-meta' command for pep517 projects. Ref #26.

Author: jaraco

pep517/build-meta.py

@@ -0,0 +1,87 @@
+"""Build metadata for a project using PEP 517 hooks.
+"""
+import argparse
+import logging
+import os
+import contextlib
+import pytoml
+import shutil
+import errno
+import tempfile
+
+from .envbuild import BuildEnvironment
+from .wrappers import Pep517HookCaller
+
+log = logging.getLogger(__name__)
+
+
+@contextlib.contextmanager
+def tempdir():
+    td = tempfile.mkdtemp()
+    try:
+        yield td
+    finally:
+        shutil.rmtree(td)
+
+
+def _prep_meta(hooks, env, dest):
+    reqs = hooks.get_requires_for_build_wheel({})
+    log.info('Got build requires: %s', reqs)
+
+    env.pip_install(reqs)
+    log.info('Installed dynamic build dependencies')
+
+    with tempdir() as td:
+        log.info('Trying to build metadata in %s', td)
+        filename = hooks.prepare_metadata_for_build_wheel(td, {})
+        source = os.path.join(td, filename)
+        shutil.move(source, os.path.join(dest, os.path.basename(filename)))
+
+
+def mkdir_p(*args, **kwargs):
+    """Like `mkdir`, but does not raise an exception if the
+    directory already exists.
+    """
+    try:
+        return os.mkdir(*args, **kwargs)
+    except OSError as exc:
+        if exc.errno != errno.EEXIST:
+            raise
+
+
+def build_meta(source_dir, dest=None):
+    pyproject = os.path.join(source_dir, 'pyproject.toml')
+    dest = os.path.join(source_dir, dest or 'dist')
+    mkdir_p(dest)
+
+    with open(pyproject) as f:
+        pyproject_data = pytoml.load(f)
+    # Ensure the mandatory data can be loaded
+    buildsys = pyproject_data['build-system']
+    requires = buildsys['requires']
+    backend = buildsys['build-backend']
+
+    hooks = Pep517HookCaller(source_dir, backend)
+
+    with BuildEnvironment() as env:
+        env.pip_install(requires)
+        _prep_meta(hooks, env, dest)
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument(
+    'source_dir',
+    help="A directory containing pyproject.toml",
+)
+parser.add_argument(
+    '--out-dir', '-o',
+    help="Destination in which to save the builds relative to source dir",
+)
+
+
+def main(args):
+    build_meta(args.source_dir, args.out_dir)
+
+
+if __name__ == '__main__':
+    main(parser.parse_args())