Re: [Chicken-users] hacking the mailbox egg

[Kon Lovett]

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On Jan 7, 2007, at 10:14 AM, minh thu wrote:

> Hi,
>
> I'd like to write a small library along the lines of the mailbox egg.
> The goal is to have a queue where the elements are ordered by some
> kind of value attached to them (in my case, it will be the moment when
> the element has to be extracted from the queue).

So essentially a priority queue.

> Reading the code, and being fairly new to scheme and chicken, I have
> some questions:
>
> - why is there a queue.scm file ? Is it because usage of the extras
> unit can be disabled ?

No. Because the extras unit doesn't disable interrupts. Mailbox  
doesn't synchronize access to its globals explicitly but disables  
interrupts, so the entire file is a critical-section.

> - what are those ##sys#xxx and ##core#xxx functions ?
>  is it permitted (good style) to use them ? where are they  
> documented ?

Permitted, yes.

Good style? Well, I wouldn't use them unless necessary, or unless  
hacking in someone else's code that does use them. You may notice  
that 'queue.scm' defines wrappers around the '##sys' access routines  
so the main body of the code calls very few directly. And some  
operations are just not available outside of the sys namespace, in  
which case they must be used.

Documented, no.

> When/if I complete the writing of such a library, would it be good to
> add it to Eggs Unlimited ?
> Have you an idea for its name ? ordered-mailbox ?

Sure.

> Thanks a lot
> vo minh thu
>
>
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