Add flag alias feature to rename old flag smoothly

[GoogleCodeExporter]

For a long term project, there exist some misnamed flags, such as missing 
currect prefix, or module name changed. if we changed the name, the 
code/running system will be broken.

Consider introduce a alias mechanism to resolve this problem.

// Modified flag with new correct name
DEFINE_int32(xfs_master_port, 8000, "some bool value");

// Compatible old name for xfs_master_port
DEFINE_int32_alias(master_port, xfs_master_port);

Run:
$ ./gflags_test --xfs_master_port=2 --help
  Flags from thirdparty/gflags/gflags_test.cpp:
    --master_port (compatible old name of 'xfs_master_port')
      type: int32 default: 8000 currently: 2
    --xfs_master_port (some bool value) type: int32
      default: 8000 currently: 2

I've implemented this feature, see the attach.

Original issue reported on code.google.com by chen3feng on 28 Jan 2013 at 1:22

Attachments:

• gflags-alias.diff