[ros-users] error: cannot load message class. Are you messages built?

[Gonçalo Cabrita]

Thanks Ken, it worked!!

However Ugo's reply got me thinking...

So if I make a ROS pkg and want to share it with colleagues or online, is
there any command I can run to "clean" the pkg, like "rosmake --pre-clean
pkg-name" (I didn't try this yet)?

Thanks for the help guys,

Gonçalo Cabrita
ISR - University of Coimbra
Portugal


On Thu, Aug 12, 2010 at 5:57 PM, Ken Conley <kwc at willowgarage.com> wrote:

> You will need to delete src/ardusim/msg/*.py as well.
>
> I general, there are a lot of problems copying compiled code trees
> from one platform to another. In this case, there is the
> incompatibilities of:
>
>  * Mac->Ubuntu
>  * cturtle -> boxturtle
>
> Both of those are likely to cause problems.
>
> HTH,
> Ken
>
> 2010/8/12 Gonçalo Cabrita <goncabrita at gmail.com>:
> > Thanks for your replies guys!
> >
> > I'm pretty sure ROS_PACKAGE_PATH is set correctly. Ardusim was already in
> the Eee PC, I just deleted it and copied the new version from my computer. I
> deleted everything in the build folder and run rosmake ardusim. Everything
> went as usual. I also checked for the build msg line at the cmake file.
> >
> > I've tried to delete everything and leave only the code inside src and
> the .msg files inside msg hoping there could be something that came from
> cturtle that is not allowing it to run in boxturtle, but still after
> everything compiles fine rostopic echo is not running.
> >
> > I'll try recording some data with rosbag and write a small node to read
> the published topics. If the problem is just with rostopic echo I should be
> able to continue my work. On the other hand I must find out what's wrong or
> I wont be able to sleep tonight! :D
> >
> > Gonçalo Cabrita
> > ISR - University of Coimbra
> > Portugal
> >
> > On Aug 12, 2010, at 5:27 PM, Ken Conley wrote:
> >
> >> This message usually occurs when rostopic cannot load
> >> ardusim/src/ardusim/msg/_TPA.py, which it needs to deserialize the
> >> messages it echos. The rest of the tests with type/show/etc... don't
> >> need the .py file, which is why they don't error.  I would attempt to
> >> rebuild the ardusim package and check for errors. I would also make
> >> sure that ardusim is on your ROS_PACKAGE_PATH.
> >>
> >> - Ken
> >>
> >> 2010/8/12 Gonçalo Cabrita <goncabrita at gmail.com>:
> >>> Hi guys!
> >>>
> >>> I have made an ROS node for reading sensors connected to an arduino.
> Along with the node I created some ROS msgs for the sensors. I compiled and
> tested everything on my MacBook running Ubuntu 10.04 with cturtle, however,
> when I copy the node to the robots (Eee PC also with Ubuntu 10.04 with
> boxturtle) I run into some problems.
> >>>
> >>> Everything compiles fine, and the node runs just fine, however I cannot
> rostopic echo my custom msgs! It gives me this error:
> >>>
> >>> error: cannot load message class for [ardusim/TPA]. Are you messages
> built?
> >>>
> >>> The topics show up on rostopic list. I can run rostopic type and rosmsg
> show. I've also tried roswtf but everything seems fine.
> >>>
> >>> What am I missing here? Could it have something to do with having
> cturtle on one computer and boxturtle on the other? The node was created on
> the MacBook with boxturtle previous to the cturtle update.
> >>>
> >>> Thanks for the help,
> >>>
> >>> Gonçalo Cabrita
> >>> ISR - University of Coimbra
> >>> Portugal
> >>> _______________________________________________
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> >>>
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