Clearer help in gclient-new-workdir.py

This modification make gclient-new-workdir.py display explicit error messages instead of cryptic Python backtraces.

BUG=

Review URL: https://codereview.chromium.org/68213010

git-svn-id: svn://svn.chromium.org/chrome/trunk/tools/depot_tools@235408 0039d316-1c4b-4281-b951-d872f2087c98

gclient-new-workdir.py

@@ -11,75 +11,93 @@ import os
 import shutil
 import subprocess
 import sys
+import textwrap
 
 
-def parse_options(argv):
-  assert not sys.platform.startswith("win")
+def print_err(msg):
+  print >> sys.stderr, msg
 
-  if len(argv) != 3:
-    print("usage: gclient-new-workdir.py <repository> <new_workdir>")
-    sys.exit(1)
 
-  repository = argv[1]
-  new_workdir = argv[2]
+def usage(msg=None):
+
+  if msg is not None:
+    print_err('\n' + textwrap.dedent(msg) + '\n')
+    usage_msg = 'Run without arguments to get usage help.'
+  else:
+    usage_msg = '''\
+    usage: %s <repository> <new_workdir>
+
+    Clone an existing gclient directory, taking care of all sub-repositories
+    Works similarly to 'git new-workdir'.
+
+    <repository> should contain a .gclient file
+    <new_workdir> must not exist
+    ''' % os.path.basename(sys.argv[0])
+
+  print_err(textwrap.dedent(usage_msg))
+  sys.exit(1)
+
+
+def parse_options():
+  if sys.platform == 'win32':
+    usage('This script cannot run on Windows because it uses symlinks.')
+
+  if len(sys.argv) != 3:
+    usage()
+
+  repository = os.path.abspath(sys.argv[1])
+  new_workdir = sys.argv[2]
 
   if not os.path.exists(repository):
-    print("Repository does not exist: " + repository)
-    sys.exit(1)
+    usage('Repository does not exist: ' + repository)
 
   if os.path.exists(new_workdir):
-    print("New workdir already exists: " + new_workdir)
-    sys.exit(1)
+    usage('New workdir already exists: ' + new_workdir)
 
   return repository, new_workdir
 
 
-def main(argv):
-  repository, new_workdir = parse_options(argv)
+def main():
+  repository, new_workdir = parse_options()
 
-  gclient = os.path.join(repository, ".gclient")
+  gclient = os.path.join(repository, '.gclient')
   if not os.path.exists(gclient):
-    print("No .gclient file: " + gclient)
+    print_err('No .gclient file: ' + gclient)
 
-  gclient_entries = os.path.join(repository, ".gclient_entries")
-  if not os.path.exists(gclient_entries):
-    print("No .gclient_entries file: " + gclient_entries)
-
-  os.mkdir(new_workdir)
-  os.symlink(gclient, os.path.join(new_workdir, ".gclient"))
-  os.symlink(gclient_entries, os.path.join(new_workdir, ".gclient_entries"))
+  os.makedirs(new_workdir)
+  os.symlink(gclient, os.path.join(new_workdir, '.gclient'))
 
   for root, dirs, _ in os.walk(repository):
-    if ".git" in dirs:
+    if '.git' in dirs:
       workdir = root.replace(repository, new_workdir, 1)
-      make_workdir(os.path.join(root, ".git"),
-                   os.path.join(workdir, ".git"))
+      make_workdir(os.path.join(root, '.git'),
+                   os.path.join(workdir, '.git'))
 
 
 def make_workdir(repository, new_workdir):
-  print("Creating: " + new_workdir)
+  print('Creating: ' + new_workdir)
   os.makedirs(new_workdir)
 
   GIT_DIRECTORY_WHITELIST = [
-    "config",
-    "info",
-    "hooks",
-    "logs/refs",
-    "objects",
-    "packed-refs",
-    "refs",
-    "remotes",
-    "rr-cache",
-    "svn"
+    'config',
+    'info',
+    'hooks',
+    'logs/refs',
+    'objects',
+    'packed-refs',
+    'refs',
+    'remotes',
+    'rr-cache',
+    'svn'
   ]
 
   for entry in GIT_DIRECTORY_WHITELIST:
     make_symlink(repository, new_workdir, entry)
 
-  shutil.copy2(os.path.join(repository, "HEAD"),
-               os.path.join(new_workdir, "HEAD"))
-  subprocess.check_call(["git", "checkout", "-f"],
-                        cwd=new_workdir.rstrip(".git"))
+  shutil.copy2(os.path.join(repository, 'HEAD'),
+               os.path.join(new_workdir, 'HEAD'))
+  subprocess.check_call(['git', 'checkout', '-f'],
+                        cwd=new_workdir.rstrip('.git'))
 
 
 def make_symlink(repository, new_workdir, link):
@@ -92,4 +110,4 @@ def make_symlink(repository, new_workdir, link):
 
 
 if __name__ == '__main__':
-  sys.exit(main(sys.argv))
+  sys.exit(main())