Terminal API: Terminal object should include PID of the launched terminal

[daviwil]

The new terminal API is looking great! It'd be really helpful to me if I could get the process ID of the launched terminal as a property on the Terminal object. I need this information in the PowerShell extension to help coordinate with my debug adapter.

Also: could there possibly be a promise return type from createTerminal so that the Terminal only gets returned after the process is started, or maybe a different way like having an event on the Terminal object that is returned?

[Tyriar]

Exposing the PID and/or related info is to be explored in #11422. It would be useful if you could say on that issue exactly what you will do with the PID when you have it.

On createTerminal returning a promise, it was originally like this and @jrieken said that we normally hide the promise behind the scenes. So what happens now is that all calls on the Terminal returned by createTerminal are queued until the process is ready and then they're sent, so it should work roughly the same as a promise by just using it immediately after createTerminal. Example here: https://github.com/Microsoft/vscode-extension-samples/blob/70e8e730636549678703ba779aa2eaf5b309ecc4/terminal-example/src/extension.ts#L50

[daviwil]

Thanks Daniel! The API approach you mention makes sense. I left a comment on the other issue to explain what I'd use the PID for.