Massive overhaul for gcl help

Massive overhaul for gcl help

Automatically generate help and enforce stricter argument parsing.
Stops from throwing an exception when run outside a subversion checkout.
Fixed gcl lint.

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=48386

[M-A Ruel, 2010-05-27 01:41:44]

Here's some examples:


> gcl help
Usage: gcl <command> [options]

Prints this help or help for the given command.
Wrapper script around Rietveld's upload.py that simplifies working with groups
of files.

version 1.2

Commands are:
  change       Creates or edits a changelist.
  changes      Lists all the changelists and their files.
  commit       Commits the changelist to the repository.
  delete       Deletes a changelist.
  deleteempties Delete all changelists that have no files.
  description  Prints the description of the specified change to stdout.
  diff         Diffs all files in the changelist or all files that aren't in a
CL.
  help         Prints this help or help for the given command.
  lint         Runs cpplint.py on all the files in the change list.
  nothave      Lists files unknown to Subversion.
  opened       Lists modified files in the current directory down.
  passthru     Everything else that is passed into gcl we redirect to svn.
  presubmit    Runs presubmit checks on the change.
  rename       Renames an existing change.
  settings     Prints code review settings for this checkout.
  status       Lists modified and unknown files in the current directory down.
  try          Sends the change to the tryserver to do a test run on your code.
  upload       Uploads the changelist to the server for review.


> gcl help lint
Usage: gcl lint <change_list> [options] 

Runs cpplint.py on all the files in the change list.

Checks all the files in the changelist for possible style violations.


> gcl help settings
Usage: gcl settings 

Prints code review settings for this checkout.

[jam, 2010-05-27 02:35:42]

lgtm, although I'm not familiar with some of the Python features you're using so
this is mostly a rubber stamp

[M-A Ruel, 2010-05-27 13:12:43]

On 2010/05/27 02:35:42, John Abd-El-Malek wrote:
> lgtm, although I'm not familiar with some of the Python features you're using
so
> this is mostly a rubber stamp

To recap;

dir(sys.module[__name__]) returns all the names (as string) of every 'named
objects' defined in this module, gcl.py. The named objects are the variable,
classes, functions and imports. So the code then filters out anything that
doesn't start with 'CMD' and the remaining ones are the supported subcommands.

For the decoration, there is 2 types. The ones without () and the active
function calls with ().

The ones that aren't a function call like @no_args is called once to return a
function object that will replace the function. I could have rewritten this as:

def tmpCMDopened():
  pass

CMDopened = no_args(tmpCMDopened)

So in fact it's the 'hook' function defined in no_args that is called, processes
'args' and then call the original function.

For attrs(), it's a bit different. The behavior is similar to:

def tmpCMDdiff(args):
  pass

CMDdiff = attrs(usage='<svn options>')(tmpCMDdiff)

In practice attrs doesn't install a hook but it _could_ have. It just modifies
the object.

For **kwargs, it's just a way to get all the arguments as a dictionary. i.e. for
attrs(usage='foo'), kwargs = { 'usage', 'foo' }