Custom Action Message Compilation


I am on completing actions_quiz today. When I was looking for an extra information about creating custom action messages, I have seen a video of constructsim on youtube (15:58) about that. I have realized that the instructor has written geometry_msgs_msgs instead of geometry_msgs as build_depend in package.xml. Yet, the program has been compiled successfully somehow. I have tried the same thing, but it has not been compiled. It throws cmake error. This is confusing. What is the reason for that? Thanks.

What is the exact error being thrown?

Hi @bayodesegun,

I have tried again. Yes, this time it did not throw any error. Whether I write geometry_msgs_msgs or geometry_msgs, it is compiled successfully. But why?

That’s an indication that it’s not necessary to include it in the first place. Try removing it completely and see what happens.

That’s sooo weird :confused: I have removed all geometry_msgs from package.xml both one-by-one and completely and compiled the system in all the way. It is still compiled. I mean, I realized that we don’t need to modify package.xml at all. So what is the reason for that we are modifying package.xml? That experiment showed that I don’t know anything about creating custom message and why I modify the package.xml file. Really need help for understanding that :thinking:

Generally, you shouldn’t need to include any of the standard messages as a dependency, and whatever dependency you include at package creation time will be added to package.xml automatically. Including these are sometimes out of overzealousness :slight_smile:.

Everything you need to get an action running is in the notes. if that doesn’t work for you, please contact us here. On this note, please let’s see the specific error being thrown. It might have a different reason entirely.

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