QUESTION:
As we can see above, we will need several new constructs in order to support features in our roadmap. We have the choice of making them all top level constructs, making the error recovery in the parser a lot more complicated, or we can re-use our declare construct to define these new structures as I presented in the pseudo-code above. Any pros/cons you can see in such approach?

I doubt the "a lot more complicated". I'd much rather have a "natural language" with a lean syntax than the cobol-ish agglomeration of keywords. Structured/syntax assisted editing should take care of gross errors so that recovery isn't as important as without these aids.

I vote for OPTION 2. I'm very much against OPTION 3.

Wolfgang

OPTION 1 (more verbose, but simpler and more stable):
<epDeclaration> ::= declare entry-point <epName> [, <epName]*
<windowDeclaration> ::= declare window <windowName> <restOfTheWindowDeclaration> end

<typeDeclaration> ::= declare [type] <typeName> <restOfTheTypeDeclaration> end

OPTION 2 (makes error recovery harder, but it is less verbose):
<epDeclaration> ::= entry-point <epName> [, <epName]*
<windowDeclaration> ::= window <windowName> <restOfTheWindowDeclaration> end
<typeDeclaration> ::= declare <typeName> <restOfTheTypeDeclaration> end

OPTION 3:
<epDeclaration> ::= someOtherKeyword entry-point <epName> [, <epName]*
<windowDeclaration> ::= someOtherKeyword window <windowName> <restOfTheWindowDeclaration> end

<typeDeclaration> ::= declare [type] <typeName> <restOfTheTypeDeclaration> end

Edson

--
Edson Tirelli
JBoss Drools Core Development
JBoss by Red Hat @ www.jboss.com

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