[ros-users] calling a service in rospy without a type

[Ken Conley]

On Fri, Jun 18, 2010 at 5:20 PM, Rosen Diankov <rosen.diankov at gmail.com> wrote:
> Given your prowess in python, it is surprising you are arguing for the
> strong-typed case.

ROS messages are strongly typed. It's not really a question of Python
favoring duck-typing, because it has to express the type and
dependency requirements of what it interfaces with.

> There are cases where being able to call a service without knowing its
> type could make it robust to the plethora of custom messages created
> by ROS users.
>
> As for overlooking package dependencies, with python this is not a
> problem. If the package path is sent with the type, then rospy can
> auto-generate the python class without relying on a pre-generated
> class to include; and I'm sure you can come up with a caching scheme
> to make this quicker the next time around.

Google Protocol Buffers do auto-generate the Python class from their
description, so it is a possibility. However, the predominant request
I get is to make rospy have better performance and less latency. I'm
exploring whether or not rosh provides a natural boundary to express
these opposing requirements.

 - Ken