Thread View: comp.sys.acorn.tech
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Started by Andrew Black
Wed, 27 Jan 1993 12:28
RISCOS_lib and alternatives
Author: Andrew Black
Date: Wed, 27 Jan 1993 12:28
Date: Wed, 27 Jan 1993 12:28
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burke@vxdesy.desy.de (Stephen Burke) writes > It actually took me a while to realise that you can have more than one >polling loop in a program - obvious in retrospect, of course. I don't think >I've ever seen it suggested in a magazine article, though. I have always wondered why a classic ARC program written in basic has one polling loop and a mighty great dispatch code. It makes following what is going on very dificult; there is no context information that Wimp_message_xyz will turn up after you have (say) put dialogue box up or send some other message. I deduced that a library that hid WIMP_POLLS from the programmer would make life a lot easier. In my naivity I assumed that RISCOS_lib was the thing to go for. RISCOS_lib seems to be depricated in the refined circles of COMP.SYS.ACORN Perhaps someone could summarise what the problems are with RISCOS_lib, and what the alternatives are? (There has been some detailed correspondance on this subject, but must confess to not having followed the details - please don't flame me for going over old ground ;-) ) --------------------------------------------------------------- Andrew Black blacka@logica.co.uk
Re: RISCOS_lib and alternatives
Author: Ian Palmer
Date: Wed, 27 Jan 1993 13:19
Date: Wed, 27 Jan 1993 13:19
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In article <1993Jan27.122843.99@condor> blacka@logica.co.uk (Andrew Black) writes:
>
>Perhaps someone could summarise what the problems are with RISCOS_lib,
>and what the alternatives are? (There has been some detailed
>correspondance on this subject, but must confess to not having
>followed the details - please don't flame me for going over old ground
>;-) )
>
I can't speak for anyone apart from me, but the main problems I have
with RiscOSLib are as follows.
As a programmer I like to be in control. As far as I'm concerned a
library should supply (in general) tools to make life easier. In this
respect consider tools that I like as leaves in the program tree.
The real problem with libraries such as RiscOSLib (and it is in no way
the only on like this, for example the Motif library for X, etc.) as
far as I'm concerened is that they interrupt the tree structure of the
program by placing a procedure (or more than one) which is fundimental
mid way into the tree (ie. wimp_poll). Thus you, as the programmer,
need to (during initialisation) spend a great deal of code attatching
things to event handlers. When things start to go wrong you can't find
out about it. For example :
Say I attatch an event handler to some event in ROLib. If this doesn't
ever get called, for some reason, how do I find out why? All I know is
that the wimp_poll function is eneterd into and then it exits again -
very handy.
This would be helped if RiscOSLib came with source, but it wouldn't
get away from the problem that it tries to do too much for the
programmer (which sounds like a good idea, but in reallity isn't).
RiscOSLib would be much improoved if it allowed the programmer to take
control of the program. I don't object to also allowing a system where
by the library can take control, as long as it is optional (which
isn't really the case in RiscOSLib).
Just as a matter of interest, has anyone worked out a way (if there is
one) of making (or persuading) RiscOSLib's saveas library to use the
RO3 drag-a-sprite if appropriate - or does it need total replacement
(ie. by the updated RiscOSLib that Acorn keep telling us isn't
necessary, but must exist internally).
Ian
--
E-mail : ijp@doc.ic.ac.uk
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