[plt-scheme] pre-release documentation disappeared? Also, where is WAIT-FOR-IO-TO-COMPLETE?

From: Danny Yoo (dyoo at hkn.eecs.berkeley.edu)
Date: Sun Nov 26 21:14:19 EST 2006

>> In DivaScheme, I find myself hitting a race condition between DivaScheme 
>> and DrScheme: I'm trying to avoid touching the interaction buffer while 
>> evaluation is taking place.  I was hoping to put something like:
>>     (define (update-text text)
>>         (wait-for-io-to-complete)
>>         ... )
>> within my code.  I've grepped for it, but I haven't found 
>> wait-for-io-to-complete anywhere in the DrScheme code base.
> Probably this isn't the way to do this -- the way to avoid race 
> conditions is to do all of the modification of the drscheme editor on 
> the thread of drscheme's eventspace.

Ah, ok; that means that I was (am?  *grin*) confused and don't know what 
I'm talking about yet.

I thought that repl interaction ran on a separate thread of execution from 
the drscheme main thread, having glanced through the DrScheme source code. 
I had assumed that when something is being executed, that the userspace 
thread somehow locks the interaction text% from edits outside the 
userspace thread, and that WAIT-FOR-IO-TO-COMPLETE was a way for the 
DrScheme thread to wait for the userspace evaluation thread to release its 
semaphore.  I now think I was wrong about that.

I took a close look at my bug, and saw that it really to do with a 
separate issue: my code had been trying to munge with repl prompt snips 
("> "), which are read-only snippets (as they should be!).  So that's why 
my text% mixin code was reporting (CAN-INSERT? ...) as false.

I found a workaround for my problem, so finding WAIT-FOR-IO-TO-COMPLETE is 
less urgent than it was before.

Posted on the users mailing list.