Multiple terminal support

[tmontes]

Random thoughts:

• On running, the kernel would create and initialise a default terminal, associated to stdin/stdout.
• A new (set of?) kernel traps/apis would allow terminal management:
  • terminal-create would create and initialise a new terminal.
  • With no arguments, the TTY associated to stdin/stdout is assumed.
  • If passed an argument, probably a TTY dev file, it would identify the new terminal.
  • If a matching terminal exists, no creation/initialisation is done; the existing terminal object is returned.
  • Not sure we would need/want a terminal-destroy... But implementation should be simple.
• The direct-print and direct-clear traps would become methods on the terminal object.
• Windows would be associated to specific terminals (defaulting to the default terminal).
• Maybe keyboard input traps like read-key could also be associated to a terminal.
• Additional terminals could be passed to the ppytty entry point script such that they would be automatically created and initialised, being ready to to use by driven tasks/presentations.

More notes:

• We probably won't be getting SIGWINCH signals from "secondary" terminals.
• Maybe a different, cleaner approach will be needed.

[tmontes]

More ideas:

• Non-default terminals are "remote" by nature accessed via a TCP connection (and maybe UNIX socket, but less portable).
• Command line client could be called with specific arguments such that it would behave as a "remote terminal", driven by the "main" ppytty running process.
• There could be two kinds of remote terminals:
  • Secondary ones, fully independent with optional input support, useful for things like presenter notes.
  • Mirror ones, which would just mirror what's being displayed in the default terminal, useful for broadcast-like scenarios.
• Implementation thoughts:
  • Connection establishment and "terminal type" detection may need a bit of work.
  • Other than that, tracking multiple terminals in the kernel state seems a natural evolution.
  • Implementing a network-backed variation of the terminal class seems very doable.