Generating pkg config files inside of disutils' setup.py

gross.py

### XXX: The following is a hack. py2cairo looks for xpyb.pc when configuring.
### However (as near as I can find) there is no way to get it to install with
### distutils, so we fake it here.
# make xpyb.pc file
class PCOpt(object):
    def __init__(self, replace_str, val):
        self.replace_str = replace_str
        self.val = val

def gen_pc():
    # --root is provided when doing maintainer type things, so set the prefix
    # to local in that case, or /usr/local when doing normal things.
    rootarg = filter(lambda a: a.startswith('--root'), sys.argv)
    try:
        rootarg = rootarg[0].split('=')[1]
    except IndexError:
        rootarg = ''
    if rootarg:
        prefix = '/usr'
    else:
        prefix = '/usr/local'

    pc_opts = {
        '--prefix': PCOpt('@prefix@', prefix),
        '--exec-prefix': PCOpt('@exec_prefix@', '${prefix}'),
        '--install-lib': PCOpt('@libdir@', '${exec_prefix}/lib'),
        '--install-headers': PCOpt('@includedir@', '${prefix}/include/python2.7/xpyb'),
        # please don't actually use this :-)
        '--dont-set-the-xcb-version': PCOpt('@PACKAGE_VERSION@', VERSION),
    }
    def override_arg(arg):
        for (k, v) in pc_opts.items():
            if arg.startswith(k):
                try:
                    v.val = arg.split('=')[1]
                except IndexError:
                    pass
    for arg in sys.argv:
        override_arg(arg)

    with open('xpyb.pc.in') as in_:
        pc = in_.read()
    with open('xpyb.pc', 'w') as out:
        for opt in pc_opts.values():
            pc = pc.replace(opt.replace_str, opt.val)
        out.write(pc)

    # if we're not installing, don't install the .pc
    if 'install' not in sys.argv:
        return

    def resolve(path):
        """ Resolve a path through pkgconfig variables. """
        for opt in pc_opts.values():
            name = '${' + opt.replace_str[1:-1] + '}' # strip off @s
            if name in path:
                path = path.replace(name, opt.val)
                path = resolve(path)
        return path

    # XXX: moar haxxx: here we strip off the leading slash to keep join() happy
    install_path = resolve(pc_opts['--install-lib'].val).strip('/')
    pkgconfig = os.path.join(rootarg, install_path, 'pkgconfig')
    try:
        os.makedirs(pkgconfig)
    except OSError as e:
        if e.errno == errno.EEXIST:
            pass
        else:
            raise
    copyfile('xpyb.pc', os.path.join(pkgconfig, 'xpyb.pc'))