[antlr-interest] postmortem

[Johannes Luber]

Jim Idle schrieb:
> 
>> -----Original Message-----
>> From: antlr-interest-bounces at antlr.org [mailto:antlr-interest-
>> bounces at antlr.org] On Behalf Of Andy Tripp
>> Sent: Wednesday, March 12, 2008 9:50 AM
>> To: antlr-interest
>>
>> * The original poster, having invested a few minutes to vent the
>> frustrations of himself
>>    and certainly at least a few others who didn't bother, goes on his
>> merry way. No
>>    ANTLR documentation has changed. 
> 
>> No warning message from ANTLR
>> saying
>>    "you don't have any ^ characters in your grammar, so you'll get a
>> flat AST, see the
>>    section on building ASTs in the book". 
> 
> And just how is the tool supposed to know that that isn't what you want?
 > Deus Ex Machina? :-) I see a lot of suggestions for warnings and errors
 > and so on that surely seem reasonable to the requester, but in fact are
 > specific to their particular situation. If you start spitting out 
warnings
 > saying "You don't have any ^ characters", all you are going to do is
 > annoy those who know about that, and confuse those that don't. Further,
 > other than giving a link to a precise article on tree construction, there
 > isn't much information you can give out in a line or two of warnings.
 > Further still, at what point does this warning go away? When there 
are two
 > ^ characters? 7? One on every production? Perhaps you were trying to
 > illustrate a point, but the example isn't a good one.
> 
Theoretically one could introduce options to suppress certain warnings 
entirely. I suppose that one could categorize the warnings and say "I'm 
not trying to do A, so warnings for not doing A are senseless to me.". 
Noting down an explicit opt-out would be also self-documenting. On the 
other side, it would result in having to think a bit about the actual 
goals, but that's not a bad thing. But I don't know enough about ANTLR 
and languages to tell if my idea is actually feasible.

Johannes