[tmql-wg] Error conditions

[Lars Marius Garshol]

* Robert Barta
>
> A bit, yes. At least we would have a list (maybe 10?, just guessing)
> errors named.

We could, but IMHO it's more important to finish TMQL than to include  
this list. Anything we add to the language extends the time it takes  
to finish.

* Lars Marius Garshol
>
>  - causes problems for implementors, because error situations tend to
>    be highly dependent on implementation strategy, and

* Robert Barta
>
> OK, that should actually not happen. If the query is valid, then a
> processor MUST perform, regardless how it is implemented.

Yes, and if it is an error, the processor MUST NOT perform. So we  
agree on that. What I meant is that it's more work for an  
implementation to distinguish error situation A from error situation  
B than it is to simply say "this query is wrong". Of course, better  
error reports make for a better query processor, but that's a choice  
for the developer to make. Some XML parsers (Ælfred, XP) simplify  
things by simply reporting everything as a "syntax error".

My experience is also that if you choose a different implementation  
strategy from others you may find distinguishing between errors A and  
B quite a bit harder.

--Lars M.