roslaunch-to-dot.py 文件源码

def __onEnvSubstitutionArg(self, env):
        '''Handle the ROS launch 'env' or 'optenv' substitution argument which
        aims to substitute the value of an environment variable inside of
        some text.

        * package -- the package to find

        '''
        # Determine if a default value was supplied
        parts = env.split(" ")
        if len(parts) == 1:
            #### No default value was supplied
            if parts[0] not in environ:
                raise Exception(
                    "Could not find environment variable: '%s'" % env)
            return environ[env]
        else:
            #### A default value was supplied
            env, default = parts
            return environ.get(env, default)