[plt-scheme] Grafting a console onto universe, hackety hack.

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Wed Jun 2 22:24:51 EDT 2010

On Jun 2, 2010, at 7:19 PM, Jordan Johnson wrote:

>    1) whether there's a decent (and minimally intrusive) way to hook into
>      universe to trigger events from this console -- polling a state variable
>      in the tick handler is kinda icky

I am trying to figure what exactly you're trying to achieve. 
I have parameterized the 'world' over many things with mixins 
and all, but I have not considered a reuse where you want to 
bring events from somewhere else. I think it should be possible
to expose some private interface -- if I knew what you wanted. 

>    2) whether there's any locking I'd need to do to make it safe for both the
>      user-input-callback (see below) and a universe/big-bang event handler
>      callback to call append-line as I'm doing below

When you write GUI programs, you are writing concurrent programs. 
There are at least two processes involved: your program and the person 
  sitting at the console. 

>    3) whether overriding on-char is really an OK way to make a text% object
>      "read-only" from the user's perspective

(send text lock #t)

>    4) whether there's already some spiffy console-style class I've missed in
>      the docs :)

Again, what are you trying to do? 

One could imagine factoring it out the drracket console. 

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