def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def disable_plugin(plugin):
    try:
        plugin = get_plugin(plugin)
    except KeyError:
        flash(_("Plugin %(plugin)s not found.", plugin=plugin.name), "danger")
        return redirect(url_for("management.plugins"))

    try:
        plugin.disable()
        flash(_("Plugin %(plugin)s disabled. Please restart FlaskBB now.",
                plugin=plugin.name), "success")
    except OSError:
        flash(_("It seems that FlaskBB does not have enough filesystem "
                "permissions. Try creating the 'DISABLED' file by "
                "yourself instead."), "danger")

    return redirect(url_for("management.plugins"))