Allow deferred service replies.

[StefanFabian]

No description provided.

[Copilot]

Pull request overview

This PR adds support for deferred service replies in ros_babel_fish, allowing service callbacks to “take” a request and send the response later (instead of always auto-sending an immediate response).

Changes:

• Update service request handling to only auto-send a response when the callback returns one.
• Extend AnyServiceCallback dispatching to support “defer response” variants by returning nullptr for deferred callbacks.
• Add a regression test ensuring deferred callbacks do not result in an early/empty response.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

File	Description
ros_babel_fish/test/service.cpp	Adds a regression test covering deferred service responses.
ros_babel_fish/src/detail/babel_fish_service.cpp	Sends a response only when the dispatched callback returns one (supports deferred replies).
ros_babel_fish/include/ros_babel_fish/detail/any_service_callback.hpp	Changes dispatch to return an optional CompoundMessage and special-cases defer variants.

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[StefanFabian]

Successfully created backport PR for kilted:

• [Backport kilted] Allow deferred service replies. #30

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[StefanFabian]

Backport failed for jazzy, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin jazzy
git worktree add -d .worktree/backport-29-to-jazzy origin/jazzy
cd .worktree/backport-29-to-jazzy
git switch --create backport-29-to-jazzy
git cherry-pick -x b53a4b9eab81ad3ca37f318bf701aa3d5b7871f8