SDK constraint and README for barback.

tools/publish_barback.py

Index: tools/publish_barback.py
diff --git a/tools/publish_barback.py b/tools/publish_barback.py
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+#!/usr/bin/env python
+#
+# Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+# for details. All rights reserved. Use of this source code is governed by a
+# BSD-style license that can be found in the LICENSE file.
+#
+# Script to push the barback package to pub. Barback is treated specially
+# because it is tightly coupled to the SDK. Pub includes its own copy of
+# barback but also includes code that is run against the user's copy of barback.
+# To ensure that those are in sync, each version of the SDK has a single
+# version of barback that it works with.
+#
+# We enforce this by placing a narrow SDK constraint in each version of barback.
+# This ensures the only barback that will be selected is the one that works
+# with the user's SDK. Once barback is more stable, we can loosen this.
+#
+# Usage: publish_barback.py
+#
+# "pub" must be in PATH.
+
+import os
+import os.path
+import re
+import shutil
+import sys
+import subprocess
+import tempfile
+
+def ReadVersion(file, field):
+  for line in open(file).read().split('\n'):
+    [k, v] = re.split('\s+', line)
+    if field == k:
+      return int(v)
+
+def Main(argv):
+  HOME = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
+  BARBACK = os.path.join(HOME, 'pkg', 'barback')
+
+  versionFile = os.path.join(HOME, 'tools', 'VERSION')
+  major = ReadVersion(versionFile, 'MAJOR')
+  minor = ReadVersion(versionFile, 'MINOR')
+  build = ReadVersion(versionFile, 'BUILD')
+  patch = ReadVersion(versionFile, 'PATCH')
+
+  # bleeding_edge has a fixed version number of 0.1.x.y . Don't allow users
+  # to publish packages from bleeding_edge.
+  if major == 0 and minor <= 1:
+    print 'Error: Do not run this script from a bleeding_edge checkout.'
+    return -1
+
+  # Convert the version to semver syntax.
+  # TODO(rnystrom): Change this when the SDK's version numbering scheme is
+  # decided.
+  if patch != 0:
+    version = '%d.%d.%d+%d' % (major, minor, build, patch)
+  else:
+    version = '%d.%d.%d' % (major, minor, build)
+
+  # Copy the package to a temp directory so we can fill in the versions in its
+  # pubspec.
+  tmpDir = tempfile.mkdtemp()
+  shutil.copytree(os.path.join(HOME, BARBACK), os.path.join(tmpDir, 'barback'))
+
+  pubspecPath = os.path.join(tmpDir, 'barback', 'pubspec.yaml')
+  with open(pubspecPath) as pubspecFile:
+    pubspec = pubspecFile.read()
+
+  # Fill in the SDK version constraint. It pins barback to the current version
+  # of the SDK with a small amount of wiggle room for hotfixes.
+  if major < 1:
+    # No breaking changes until after 1.0.
+    # TODO(rnystrom): Remove this once 1.0 has shipped.
+    constraint = '>=%d.%d.%d <1.1.0' % (major, minor, build)
+  else:
+    constraint = '>=%d.%d.%d <%d.%d.0' % (major, minor, build, major, minor + 1)
+
+  # Fill in the SDK version constraint.
+  pubspec = pubspec.replace('$SDK_CONSTRAINT$', constraint)
+
+  with open(pubspecPath, 'w') as pubspecFile:
+    pubspecFile.write(pubspec)
+
+  print ('Publishing barback %s with SDK constraint "%s".' %
+      (version, constraint))
+  subprocess.call(['pub', 'lish'], cwd=os.path.join(tmpDir, 'barback'))
+  shutil.rmtree(tmpDir)
+
+if __name__ == '__main__':
+  sys.exit(Main(sys.argv))