Re: Best way to find records in sequences?
Pete Lomax wrote:
>
> On Fri, 07 Jul 2006 04:04:57 -0700, ZNorQ <guest at RapidEuphoria.com>
> wrote:
>
> > MyErrors = {
> > {"SYN_SE", "Syntax error" },
> > "ARY_OB", "Out of range" },
> > "MEM_OO", "Out of memory" },
> > "MEM_LD", "Memory leak detected" },
> > "TOB_TM", "Too much tobacco in keyboard"}}
> Umm, if you are going to code "SYN_SE" then you may as well code
> "Syntax error"...
I used a VERY simplified example. I use indices only when the sequences
are containing large amounts of data - and usually when they contain
several fields for each record.
> > MyErrIdx = {"SYN_SE", "ARY_OB", "MEM_OO", "MEM_LD", "TOB_TM"}.
> >
> >This would ofcourse have to correspond to the same record id as in MyErrors.
> ...and that would be almost as fiddly/error-prone to keep in line with
> the error text set as using literal integers would.
Not at all. I don't do this manually - this is ofcourse created after
the MyErrors are declared by a small routine that copies all the indices
into MyErrIdx.
>
> This is what I usually do:
> }}}
<eucode>
> sequence Emsgs
> Emsgs={}
> integer Eused
> Eused = 0
> function emsg(sequence txt)
> Eused+=1
> if Eused>length(Emsgs) then
> Emsgs&=repeat(0,32)
> end if
> Emsgs[Eused]=txt
> return Eused
> end function
I'm having a real hard time understanding the above code. Well, more the
use of 'if' and 'repeat'. Why whould this be necessary? As far as I can
see, the 'if' would ALWAYS be executed as Eused would be larger than the
length of Emsgs.. Well, unless Emsgs was tampered with manually - but
that could go in any direction - either shorten the content, or adding to
it. And why repeat 32 zeroes before adding the actual text?
>
> global constant
> E_se = emsg("Syntax error"),
> E_oor = emsg("Out of range"),
> E_oom = emsg("Out of memory"),
> E_mld = emsg("Memory leak detected"),
> E_tmkik = emsg("Too much tobacco in keyboard")
>
> global function getEmsg(integer i)
> return Emsgs[i]
> end function
> </eucode>
{{{
> You have to choose a prefix which you don't think will clash with
> anything else, eg "E_", "EM_", "EI", etc. and/or use global constants
> as per the strings you used, ie SYN_SE etc. While (lots of) global
> variables is generally considered a bad thing, constants are not;
> it is actually worse to make Emsgs global, since a hidden line such as
> Emsgs=prepend(Emsgs,"I am a bug") could cause serious confusion.
> Even cryptic names such as the above make code easier to read and
> maintain than using literal integers, w/o performance loss.
> The initialisation overhead is pretty minimal.
>
Seems like a good way to do this, the only thing is that it could create
alot of constants. In my example, "SYN_SE" is just that - an example. An
index could just as well be something readable - like "Syntax error".
Remember - the example I use is just an simplified one. My error message
list is comprised of more data than just the text. Usually I have a
criticallity code, what buttons should be active on the error form, what
icon, the heading text, the body text (that could contain alot of
information), etc. etc.
I do see that the use of constants would have little or no performance
loss. I haven't done that much programming, so I couldn't comment on what
loss of performance my example would have - that would ofcourse depend on
the size of the sequence - as far as I can see. An onther thing is - how
criticial is the performance factor - well, that would perhaps depend on
what information was in the sequence. For an error message, maybe not so
critical - but for a pure "database" containing alot of information in a
game... I'm not an expert... :)
> Actually, I tend to go one step further and use e01se, e02oor, as a
> kind of second-level redundancy check; if I want a sorted list of
> error messages I block copy and paste/sort into the documentation.
> 
)
>
> HTH,
> Pete
>
>
Thanks for your feedback, Pete. It gives me ideas - like PeteS told me -
there are several ways to skin a cat.. :)
Kenneth
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