After some wrestling with the templates I have found a way to preserve the tree rewriting semantics but allow a more C like behavior for grammars whereby if the grammar programmer does not initialize a return value from a rule, then it is just left as it would be in C, being uninitialized and therefore likely to be garbage.
While this may break backwards compatibility (and so I will emphasize this in the release notes), it seems better to behave like C than Java in this respect. Because I am able to preserve the tree rewriting semantics, I feel that those few affected by this will agree that not initializing return values without being told to makes more sense in the long run. So, the ways to initialize parameters are: r returns [enum FRED = FRED_VAL1] : ... ; And the initialization will be generated for you. Or you can place initialization in the @init section of a rule, or otherwise initialize via actions. Note all the same rules apply about @after vs @finally vs exception code (see Markmail search if you don't remember seeing that email - will document for next release). I think that should keep just about everyone happy. Please remember though that the C rules return a struct unless there is only one return parameter and no tree nodes are being generated. This limits some of the things that you can declare as return types. Also, because there are some limitations in the generic parsing of the return element specs, it is quite often desirable to make a typedef of a complex declaration. Finally, passing things around in a parser instead of waiting for a tree parse is not generally a good idea anyway, because of the complications of freeing things if you hit a parsing error. Jim -- You received this message because you are subscribed to the Google Groups "il-antlr-interest" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/il-antlr-interest?hl=en.
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