Add --message field to the creation of ROS2 packages.

[leander-dsouza]

Basic Info

Info	Please fill out this column
Ticket(s) this addresses	Assists #1015
Primary OS tested on	Ubuntu

Description

• Adds the --message field to the ros2 pkg create command.
• The boilerplate for each custom message is as follows:
  MyMsg.msg

  # TODO: Define the message fields here.
  # For example:
  # bool my_flag
  # string my_string
  # int32 my_number
  

• Include a regex validation that only allows CamelCase alphanumeric message types to exist.
• The message field is restricted to only the ament_cmake build type.
• The tests have been modified to include checks for two messages - MyMsg and OtherMsg.

Usage

• You can include the --message field followed by an indefinite number of messages as follows:

  $ ros2 pkg create tutorial_interfaces --build-type ament_cmake --license Apache-2.0 --message MyMsg OtherMsg
  
  going to create a new package
  package name: tutorial_interfaces
  destination directory: <destination path>
  package format: 3
  version: 0.0.0
  description: TODO: Package description
  maintainer: ["<your name> <your email address>"]
  licenses: ['Apache-2.0']
  build type: ament_cmake
  dependencies: []
  messages: ['MyMsg', 'OtherMsg']
  creating folder ./tutorial_interfaces
  creating ./tutorial_interfaces/package.xml
  creating source and include folder
  creating folder ./tutorial_interfaces/src
  creating folder ./tutorial_interfaces/include/tutorial_interfaces
  creating ./tutorial_interfaces/CMakeLists.txt
  creating folder ./tutorial_interfaces/msg
  creating ./tutorial_interfaces/msg/MyMsg.msg
  creating ./tutorial_interfaces/msg/OtherMsg.msg   

• If you include an invalid message name, it would fail the creation step:

  $ ros2 pkg create tutorial_interfaces --build-type ament_cmake --license Apache-2.0 --message mymsg
  
  Aborted: invalid message name(s): mymsg. Message names must be CamelCase and alphanumeric (e.g. MyMsg).

• The creation step would also fail if the build type is not ament_cmake:

  $ ros2 pkg create tutorial_interfaces --build-type ament_python --license Apache-2.0 --message MyMsg
  
  Aborted: --message is only supported with 'ament_cmake' build type.

Is this user-facing behaviour change?

Yes, please refer to the Usage section for more details on how the implementation affects the user's creation of the ROS2 package.

Did you use Generative AI?

No

Additional Information

Future work can include adding fields for actions and services.

[peci1]

Thanks, I have a few small comments, but nothing important.

[peci1]

License text is missing. However, the other template files also don't have it, so maybe let's leave it to another PR.

[leander-dsouza]

Yes, sure.
We can add the license texts to all the template files in a future PR.