Re: what's a callback?

From: John Larkin (john_at_spamless.usa)
Date: 12/20/04 

Date: Mon, 20 Dec 2004 08:17:30 -0800

On Mon, 20 Dec 2004 10:12:58 GMT, "Anthony Fremont"
<spam@anywhere.com> wrote:

>John Larkin wrote:
>> On Sun, 19 Dec 2004 21:50:21 GMT, "Anthony Fremont"
>> <spam@anywhere.com> wrote:
>>
>>>
>>> "Fred Bloggs" <nospam@nospam.com> wrote in message
>>>
>>>> No- that is called "setting a flag to remind you to finish some
>>>> chores" and is an example of *re-entrant code*:-) Why in the world
>>>> would that be called "callback" unless you collect useless jargon?
>>>
>>> That's certainly the most unique definition of re-entrancy that I've
>>> seen.
>>>
>>> When I think of re-entrant code, I think of code that has no local
>>> variable storage associated to it. I also think of code that can
>>> call itself recursively or be executed in several threads across
>>> multiple processors concurrently with only one copy in memory.
>>
>>
>> AKA "pure" code.
>
>Well.....I guess if it were to be really pure code, all addresses would
>have to be relative to the instruction counter. ;-) We used to call
>this floatable code as it could be just plunked into memory anywhere and
>executed.

My (perhaps non-professional-programmer) definition of that is
"relocatable" or "PIC" (position independent) code.

"Pure" code is code that has no associated statics and if of course
not self-modifying, so that it can be executed by multiple threads
without hassle.

John

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