Make it a non-breaking change

Author: gonzalocasas

src/roslibpy/__init__.py

@@ -41,6 +41,19 @@
 Main ROS concepts
 =================
 
+ROS1 vs ROS2
+------------
+
+This library has been tested to work with ROS1. ROS2 should work, but it is still
+in the works.
+
+One area in which ROS1 and ROS2 differ is in the header interface. To use ROS2, use
+the header defined in the `roslibpy.ros2` module.
+
+.. autoclass:: roslibpy.ros2.Header
+   :members:
+
+
 Topics
 ------
 

src/roslibpy/core.py

@@ -48,10 +48,15 @@ def __init__(self, values=None):
 
 
 class Header(UserDict):
-    """Represents a message header of the ROS type std_msgs/Header."""
+    """Represents a message header of the ROS type std_msgs/Header.
 
-    def __init__(self, stamp=None, frame_id=None):
+    This header is only compatible with ROS1. For ROS2 headers, use :class:`roslibpy.ros2.Header`.
+
+    """
+
+    def __init__(self, seq=None, stamp=None, frame_id=None):
         self.data = {}
+        self.data["seq"] = seq
         self.data["stamp"] = Time(stamp["secs"], stamp["nsecs"]) if stamp else None
         self.data["frame_id"] = frame_id
 

src/roslibpy/ros2/__init__.py

@@ -0,0 +1,22 @@
+# Python 2/3 compatibility import list
+try:
+    from collections import UserDict
+except ImportError:
+    from UserDict import UserDict
+
+from roslibpy import Time
+from roslibpy import Header as ROS1Header
+
+__all__ = [
+    "Header",
+]
+
+
+class Header(ROS1Header):
+    """Represents a message header of the ROS type std_msgs/Header."""
+
+    def __init__(self, stamp=None, frame_id=None):
+        super(Header, self).__init__(stamp=stamp, frame_id=frame_id)
+        self.data["stamp"] = Time(stamp["secs"], stamp["nsecs"]) if stamp else None
+        self.data["frame_id"] = frame_id
+        del self.data["seq"]