[antlr-interest] A postmortem of my use of antler

Gerald B. Rosenberg gbr at newtechlaw.com
Tue Mar 11 11:55:38 PDT 2008


At 09:34 AM 3/11/2008, Benjamin Shropshire wrote:
>Gerald B. Rosenberg wrote:
>>At 03:08 PM 3/10/2008, Benjamin Shropshire wrote:

>Your points #12 & #13 cover a lot of what I would have liked to see 
>on the front page. (That and enough context for someone new to known 
>what they are talking about.)

Yes, but there is no practical way to fit it into one page.  Chapter, 
maybe; more likely a book.

>>The step function learning problem is largely (I believe) one of 
>>learning how to design a recognition specification subject to the 
>>available mechanics of the Antlr language operators.
>
>Oddly I was having a blast building and debugging my grammar. It was 
>when I started trying to put in actions that stuff got difficult.

Unfortunately, that is the nature of the beast.  Grammars are highly 
custom and if you don't have a good grasp of the full set of 
requirements at the outset, trying to tack on things at the end can 
really bork the whole design -- most of the time you can, but 
sometimes the change requirement trickles down to requiring a change 
in token definitions -- and that is very frustrating.

And, if there is a #16, it would be:
16) Don't try to do too much in actions; just call a method.  Any 
standard programming language is far better at procedural logic.

>>11) Unless performance is absolutely your top 6 design 
>>requirements, don't worry about using predicates.
>that would be "don't worry about what predicates /cost/"?

Yes.

>>14) Don't try to dump complex blocks from a parser or AST.  Use 
>>StringTemplate to unparse.
>Does this hold if the final output is not a text file (e.g. in 
>memory structures or a binary data file)

No and maybe.  Would be an interesting application to have 
StringTemplate operate as a directed byte code generator.


----
Gerald B. Rosenberg, Esq.
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