params.py

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import fnmatch
import rospy
import threading

from json import loads, dumps


""" Methods to interact with the param server.  Values have to be passed
as JSON in order to facilitate dynamically typed SRV messages """

# rospy parameter server isn't thread-safe
param_server_lock = threading.RLock()

def set_param(name, value, params_glob):
    if params_glob and not any(fnmatch.fnmatch(str(name), glob) for glob in params_glob):
        # If the glob list is not empty and there are no glob matches,
        # stop the attempt to set the parameter.
        return
    # If the glob list is empty (i.e. false) or the parameter matches
    # one of the glob strings, continue to set the parameter.
    d = None
    try:
        d = loads(value)
    except ValueError:
        raise Exception("Due to the type flexibility of the ROS parameter server, the value argument to set_param must be a JSON-formatted string.")
    with param_server_lock:
        rospy.set_param(name, d)
    
    
def get_param(name, default, params_glob):
    if params_glob and not any(fnmatch.fnmatch(str(name), glob) for glob in params_glob):
        # If the glob list is not empty and there are no glob matches,
        # stop the attempt to get the parameter.
        return
    # If the glob list is empty (i.e. false) or the parameter matches
    # one of the glob strings, continue to get the parameter.
    d = None
    if default != "":
        try:
            d = loads(default)
        except ValueError:
            d = default
    with param_server_lock:
        value = rospy.get_param(name, d)
    return dumps(value)

def has_param(name, params_glob):
    if params_glob and not any(fnmatch.fnmatch(str(name), glob) for glob in params_glob):
        # If the glob list is not empty and there are no glob matches,
        # stop the attempt to set the parameter.
        return False
    # If the glob list is empty (i.e. false) or the parameter matches
    # one of the glob strings, check whether the parameter exists.
    with param_server_lock:
        return rospy.has_param(name)

def delete_param(name, params_glob):
    if params_glob and not any(fnmatch.fnmatch(str(name), glob) for glob in params_glob):
        # If the glob list is not empty and there are no glob matches,
        # stop the attempt to delete the parameter.
        return
    # If the glob list is empty (i.e. false) or the parameter matches
    # one of the glob strings, continue to delete the parameter.
    if has_param(name, params_glob):
        with param_server_lock:
            rospy.delete_param(name)

def search_param(name, params_glob):
    if params_glob and not any(fnmatch.fnmatch(str(name), glob) for glob in params_glob):
        # If the glob list is not empty and there are no glob matches,
        # stop the attempt to find the parameter.
        return None
    # If the glob list is empty (i.e. false) or the parameter matches
    # one of the glob strings, continue to find the parameter.
    return rospy.search_param(name)

def get_param_names(params_glob):
    with param_server_lock:
        if params_glob:
            # If there is a parameter glob, filter by it.
            return filter(lambda x: any(fnmatch.fnmatch(str(x), glob) for glob in params_glob), rospy.get_param_names())
        else:
            # If there is no parameter glob, don't filter.
            return rospy.get_param_names()