Source Code for Module roslib.message

  1  # Software License Agreement (BSD License) 
  2  # 
  3  # Copyright (c) 2008, Willow Garage, Inc. 
  4  # All rights reserved. 
  5  # 
  6  # Redistribution and use in source and binary forms, with or without 
  7  # modification, are permitted provided that the following conditions 
  8  # are met: 
  9  # 
 10  #  * Redistributions of source code must retain the above copyright 
 11  #    notice, this list of conditions and the following disclaimer. 
 12  #  * Redistributions in binary form must reproduce the above 
 13  #    copyright notice, this list of conditions and the following 
 14  #    disclaimer in the documentation and/or other materials provided 
 15  #    with the distribution. 
 16  #  * Neither the name of Willow Garage, Inc. nor the names of its 
 17  #    contributors may be used to endorse or promote products derived 
 18  #    from this software without specific prior written permission. 
 19  # 
 20  # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
 21  # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
 22  # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 
 23  # FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 
 24  # COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 
 25  # INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 
 26  # BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 
 27  # LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER 
 28  # CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 29  # LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN 
 30  # ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 
 31  # POSSIBILITY OF SUCH DAMAGE. 
 32  # 
 33  # Revision $Id$ 
 34   
 35  """ 
 36  Support library for Python autogenerated message files. This defines 
 37  the Message base class used by genmsg_py as well as support 
 38  libraries for type checking and retrieving message classes by type 
 39  name. 
 40  """ 
 41   
 42  import genmsg 
 43   
 44  import genpy.message  # for wrapping get_message_class, get_service_class 
 45  # forward a bunch of old symbols from genpy for backwards compat 
 46  from genpy import DeserializationError  # noqa: F401 
 47  from genpy import Duration  # noqa: F401 
 48  from genpy import Message  # noqa: F401 
 49  from genpy import SerializationError  # noqa: F401 
 50  from genpy import TVal  # noqa: F401 
 51  from genpy import Time  # noqa: F401 
 52  from genpy.message import check_type  # noqa: F401 
 53  from genpy.message import fill_message_args  # noqa: F401 
 54  from genpy.message import get_printable_message_args  # noqa: F401 
 55  from genpy.message import strify_message  # noqa: F401 
 56   
 57  import roslib 
 58   
 59  import rospkg 
 60   
 61   
 62 -def _get_message_or_service_class(type_str, message_type, reload_on_error=False): 
 63      # parse package and local type name for import 
 64      package, base_type = genmsg.package_resource_name(message_type) 
 65      if not package: 
 66          if base_type == 'Header': 
 67              package = 'std_msgs' 
 68          else: 
 69              raise ValueError('message type is missing package name: %s' % str(message_type)) 
 70      pypkg = val = None 
 71      try: 
 72          # bootstrap our sys.path 
 73          roslib.launcher.load_manifest(package) 
 74          # import the package and return the class 
 75          pypkg = __import__('%s.%s' % (package, type_str)) 
 76          val = getattr(getattr(pypkg, type_str), base_type) 
 77      except rospkg.ResourceNotFound: 
 78          val = None 
 79      except ImportError: 
 80          val = None 
 81      except AttributeError: 
 82          val = None 
 83   
 84      # this logic is mainly to support rosh, so that a user doesn't 
 85      # have to exit a shell just because a message wasn't built yet 
 86      if val is None and reload_on_error: 
 87          try: 
 88              reload  # Python 2 
 89          except NameError: 
 90              from importlib import reload  # Python 3 
 91          try: 
 92              if pypkg: 
 93                  reload(pypkg) 
 94              val = getattr(getattr(pypkg, type_str), base_type) 
 95          except Exception: 
 96              val = None 
 97      return val 
 98   
 99   
100  # cache for get_message_class 
101  _message_class_cache = {} 
102   
103   
104  # cache for get_service_class 
105  _service_class_cache = {} 
106   
107   
108 -def get_message_class(message_type, reload_on_error=False): 
109      if message_type in _message_class_cache: 
110          return _message_class_cache[message_type] 
111      # try w/o bootstrapping 
112      cls = genpy.message.get_message_class(message_type, reload_on_error=reload_on_error) 
113      if cls is None: 
114          # try old loader w/ bootstrapping 
115          cls = _get_message_or_service_class('msg', message_type, reload_on_error=reload_on_error) 
116      if cls: 
117          _message_class_cache[message_type] = cls 
118      return cls 
119   
120   
121 -def get_service_class(service_type, reload_on_error=False): 
122      if service_type in _service_class_cache: 
123          return _service_class_cache[service_type] 
124      cls = genpy.message.get_service_class(service_type, reload_on_error=reload_on_error) 
125      # try w/o bootstrapping 
126      if cls is None: 
127          # try old loader w/ bootstrapping 
128          cls = _get_message_or_service_class('srv', service_type, reload_on_error=reload_on_error) 
129      if cls: 
130          _service_class_cache[service_type] = cls 
131      return cls 
132