Add interactive mode for message creation

[Flova]

As discussed in #742 this PR adds an interactive TUI to the ros2 topic pub command.

The cli is mostly kept as it is, only an additional -i or --interactive flag is added. This allows the old behavior for scripting etc. while enhancing the experience in a manual use case.

Added dependencies

• python3-prompt-toolkit
• python3-pygments

Features

• Interactive editing of the message in simple terminal editor
• YAML syntax highlighting
• Mouse support in the editor
• Storage of the last send message of a given type, so large inputs can be easily reused

Other changes:

• Slight internal restructure
• Removes parsing from the publish method
• Updates doc strings

Closes #742

The implementation for the topic pub command serves as a proof of concept. We can expand it to services and actions if the details are ironed out.

Demo

[clalancette]

I'm sorry for the long delay in getting to look at this. I do think this is a valuable feature to have, so thanks for getting it started.

That said, I have a couple of concerns with the implementation:

1. The storing of temporary files to reuse next time is clever, but I think it is doing too much in one PR. I'd rather us just get the interactive feature in first, then we can think about adding in caching separately.
2. I had to rebase this whole thing because the newly added 'auto' (for std_msgs/Header) and 'now' (for builtin_interfaces/Time) keywords touch the same code. I did that, and fixed the resulting problems, and also ended up removing the caching mechanism.
3. The way that this feature interacts with 'auto' and 'now' isn't ideal. In particular, there is no way to specify them in interactive mode. Additionally, if you pass them on the command line, and also enter interactive mode, they don't populate properly. I'm not quite sure how to fix this, but it would be really good to have them integrated.

[fujitatomoya]

Storage of the last send message of a given type, so large inputs can be easily reused

where is this come from? is this provided by python package?

I did that, and fixed the resulting problems, and also ended up removing the caching mechanism.

Ah, okay isee.

In particular, there is no way to specify them in interactive mode. Additionally, if you pass them on the command line, and also enter interactive mode

When we are using the interactive mode, can we just ask the user to fill in the contents via editor?

[clalancette]

When we are using the interactive mode, can we just ask the user to fill in the contents via editor?

Let me show you an example where it wouldn't be ideal.

Right now in Rolling, you can do this:

$ ros2 topic pub /foo nav_msgs/msg/Path '{header: {stamp: {sec: 25, nanosec: 30}}}'

And you'lll get this output:

publisher: beginning loop
publishing #1: nav_msgs.msg.Path(header=std_msgs.msg.Header(stamp=builtin_interfaces.msg.Time(sec=25, nanosec=30), frame_id=''), poses=[])

publishing #2: nav_msgs.msg.Path(header=std_msgs.msg.Header(stamp=builtin_interfaces.msg.Time(sec=25, nanosec=30), frame_id=''), poses=[])

(that's the same as in Foxy, Galactic, and Humble).

But in Rolling, you can also do this:

$ ros2 topic pub /foo nav_msgs/msg/Path '{header: {stamp: now}}'

Which will get you this:

publisher: beginning loop
publishing #1: nav_msgs.msg.Path(header=std_msgs.msg.Header(stamp=builtin_interfaces.msg.Time(sec=1666012466, nanosec=830824864), frame_id=''), poses=[])

publishing #2: nav_msgs.msg.Path(header=std_msgs.msg.Header(stamp=builtin_interfaces.msg.Time(sec=1666012467, nanosec=831668171), frame_id=''), poses=[])

(notice that the time is increasing on every publish).

If we only allow interactive mode to specify numbers for the timestamps, then we can get the previous behavior, but not the new one. It would be much nicer if this was integrated together so that it would work for users like they expect.