[MIT-Scheme-devel] signalling asynchronous, non-error conditions from microcode

[Taylor Campbell]

I've started poking about to find a way to implement SIGWINCH in
Edwin so that it can know when to resize the screen in the terminal
interface.  So far I've come up with two possible approaches:

  - Allocate a new microcode error code and signal that in the
    SIGWINCH handler.  The run-time system can turn that into a
    non-error condition and signal it in the appropriate thread.  It
    seems not quite the right thing to use microcode errors for what
    really aren't errors, though.

  - Allocate a new keyboard interrupt handler which can signal a
    resize condition in the appropriate thread.  This is a little
    better, because it's not a synchronous error but rather just an
    asynchronous signal, yet it seems wrong to allocate a keyboard
    interrupt for something that has nothing to do with the keyboard.

Neither of these seems appropriate, but I can't find any other way to
send any sort of asynchronous signal to Scheme that Edwin could pick
up with a condition handler or somesuch.  Is there a better way to do
this, or would one of these solutions suffice?