Source Code for Module roslib.params

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33  # Revision $Id: params.py 14580 2011-08-05 17:32:59Z kwc $ 
34  # $Author: kwc $ 
35  """ 
36  Utilities for accessing the Parameter Server 
37  """ 
38   
39  import sys 
40  import yaml 
41   
42  try: 
43      import xmlrpc.client as xmlrpcclient #Python 3.x 
44  except ImportError: 
45      import xmlrpclib as xmlrpcclient #Python 2.x 
46   
47  import roslib.rosenv 
48  from roslib.names import REMAP 
49   
50  _param_server = None 
51   
52 -def load_command_line_node_params(argv): 
53      """ 
54      Load node param mappings (aka private parameters) encoded in 
55      command-line arguments, e.g. _foo:=bar. See also roslib.names.load_mappings. 
56      @param argv: command-line arguments 
57      @param argv: [str] 
58      @return: param->value remappings.  
59      @rtype: {str: val} 
60      """     
61      mappings = {} 
62      for arg in argv: 
63          if REMAP in arg: 
64              try: 
65                  src, dst = [x.strip() for x in arg.split(REMAP)] 
66                  if src and dst: 
67                      if len(src) > 1 and src[0] == '_' and src[1] != '_': 
68                          mappings[src[1:]] = yaml.load(dst) 
69              except: 
70                  sys.stderr.write("ERROR: Invalid remapping argument '%s'\n"%arg) 
71      return mappings 
72   
73 -def get_param(key): 
74      """ 
75      Retrieve parameter value from the Parameter Server. Each call to this 
76      routine results in an actual network call to the Parameter Server. 
77      Client must be an actual ROS node in order to implement a parameter cache. 
78   
79      @param key: name of parameter to fetch 
80      @type  key: str 
81      @raise KeyError: if parameter is not set 
82      """ 
83      global _param_server 
84      if _param_server is None: 
85          _param_server = xmlrpcclient.ServerProxy(roslib.rosenv.get_master_uri()) 
86      code, status, value = _param_server.getParam('/roslib', key) 
87      if code != 1: #unwrap value with Python semantics 
88          raise KeyError(key) 
89      return value 
90