[racket] Behaviour with read-only files

From: John Clements (clements at brinckerhoff.org)
Date: Thu Nov 17 14:15:37 EST 2011

On Nov 17, 2011, at 11:03 AM, Robby Findler wrote:

> This seems like the kind of thing where the stepper takes control over
> the GUI in the same way that the OS can take over the GUI of a
> program. Instead of a spinning beach ball, tho, it would be good if
> the stepper dim the windows and write some message on top of them,
> telling the user to go to the stepper window to advance the program.
> I don't think that we have the right hooks for that yet, but you could
> probably do some clever namespace hacking to replace frame% with
> something that collaborated with the stepper and then use that
> namespace to start the user's program.

Oog... this all sounds really complicated. I have something really simple in mind. The user's thread increments a counter every time it sends a step to the stepper. When it gets to 10K, it sends a "here's a semaphore, I'm going to block on it" message. The stepper then throws up a modal dialog (yes, I'm guessing this blocks all of the DrRacket interface) with three(?) choices: Halt the program, keep running for another 10K steps, or keep running forever.

Shall we take this off racket-users?


> Robby
> On Thu, Nov 17, 2011 at 12:56 PM, John Clements
> <clements at brinckerhoff.org> wrote:
>> On Nov 17, 2011, at 10:53 AM, Matthias Felleisen wrote:
>>> On Nov 17, 2011, at 1:47 PM, John Clements wrote:
>>>> Suppose you run a big-bang program that puts a dot on the screen every time you press a key.  Now suppose it runs for 1K steps and halts. The user sees that the window is frozen, but probably won't figure out that the way to un-freeze it is to go to the stepper window and advance past the end of the currently-computed steps.
>>> Perhaps 'universe' should have a 'stepper' entry point so that it can signal to programmers that it is waiting for stepper input. -- Matthias
>> This sounds complicated (for you and me to implement). What would the user see?
>> John
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