Re: [xsl] Re: [answered] collecting multiple tokenize() results into one sequence

[Wendell Piez <wapiez@xxxxxxxxxxxxxxxx>]

Lars,

At 01:17 PM 7/29/2008, you wrote:
> Hi Wendell,
> "better" in what sense?
> Here, saying less may make it easier to maintain correctness of the 
> error message across all situations...
> and I grant that an error message that's incorrect or unclear for 
> the particular instance can be misleading and frustrating...
> but if a terse, correct error message leaves the programmer 
> wondering why the expression is illegal, it seems to me that it's 
> still failed an important goal of error messages.

That may be the case without the goal of "[never leaving the 
programmer] wondering why the expression is illegal" being entirely 
realistic. :-)

Beyond that, much could be said, but it wouldn't be on topic (even if 
I thought I could add to what Mike said earlier).

> On the other extreme, explanatory paragraphs and tutorials are too 
> much to expect from error messages. Maybe the best bet is to give an 
> error ID or URL or some other reference that makes it easy to look 
> up more information on why a particular error occurred.

Indeed.

> A less specific but still helpful (when true) bit of information to 
> tell the user would be that the given path requires (or, is relative 
> to) the current document. That would cover the case of initial "/", 
> key(), and maybe others that implicitly access the current document.

I don't believe the key() function is illegal as long as its 
arguments do not reference the context node. In 2.0, this can be done 
if you use the third argument to establish the context of the key 
(and this is useful).

Then too, I dare say this is just one of those things that an XSLT 
programmer who is using such advanced features as iterating over a 
sequence of atomic values simply has to get used to, through trial 
and error if need be (I'm speaking of myself here :-). For these 
purposes, even seeing the same "oh that again" error message can be 
useful even if the verbatim content of the message isn't.

Another approach is to learn that such techniques, having such 
pitfalls, might best not be regarded as methods of first resort. 
Hence, we write the grouping to select nodes, not select atomics -- 
which (if we do it right) might leave us better off entirely.

I'm aware that none of this actually contradicts your point.

> This does not explain everything to the user, but may give them the 
> missing data point that allows them to connect two seemingly unrelated dots.

In any case, it's an art. I can't count the number of occasions I 
"fixed" something for one set of users only to discover I had made 
things worse for others.

Cheers,
Wendell


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Wendell Piez                            mailto:wapiez@xxxxxxxxxxxxxxxx
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