Click/Gflags compatibiltiy.

click_gflags.py

"""
Click gflags compatibility, provides a click.Command subclass that plays
nicely with gflags, passing any unknown arguments to it and combining the
help text.

Use me like this:

@click.command(cls=GflagsCommand)
def foo(bar):
    ...
"""

import click
import gflags


class GflagsCommand(click.Command):
    """
    Click Command class that provides compatibility with gflags. Any
    arguments/options that click does not parse are passed on to gflags for its
    parsing.

    To use this in your project, use the click.command decorator like so:
    @click.command(cls=GflagsCommand)
    def my_command():
        pass
    """
    def parse_args(self, ctx, args):
        # Help gflags skip over options it doesn't know about which lack a =,
        # like: '--some_opt value'. This also allows mixing of flag and
        # non-flag arguments, which is click's default.
        gflags.FLAGS.UseGnuGetOpt()

        # Parse gflags options first. If this is done the other way around,
        # then click will try to consume gflags as Arguments instead of
        # assuming they're Options.
        gflags_args = [ctx.info_name] + args
        extra_args = gflags.FLAGS(gflags_args, known_only=True)

        # Trim program name from the extra args that gflags gives us
        extra_args = extra_args[1:]

        extra_args = super(GflagsCommand, self).parse_args(ctx, extra_args)

        return extra_args

    def get_help(self, ctx):
       """
       Get the Click help text along with the gflags help
       """
       help_text = super(GflagsCommand, self).get_help(ctx)

       help_text += "\n\n\n"
       help_text += "Additionally these options are available via gflags:\n"
       help_text += gflags.FLAGS.GetHelp()

       return help_text