I think those are generally

puredanger — Mon, 24 Mar 2008 23:10:12 -0400

I think those are generally known as Multi-Methods and are available in a few languages. Can't say I've seen anyone even considering adding them to Java 7. Maybe you can be the first. :)

Hopefully I'll have some time soon to continue playing with this!

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phuber — Sun, 23 Mar 2008 07:10:58 -0400

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Nice approach. As you said your going to further fumble around with this soon, maybe you could give us a more concrete example that in the end has a real result.

I would suggest the follwoing task: Use a Building and it's parts (stairs, windows, doors, rooms) as real world objects for your nodes hierarchie. Implement a visitor that counts all steps of all stairs and which I could then ask "int getStepsCount()" for instance.

++

Hm, btw - Why don't we get rid of visitor-double-dispatch in java 7 anyway? could we not just add/introduce a new kind of method-sematics which adds runtime-type method-dispatching instead of compiletime-type method-dispatching?

We coud just add a new keyword "runtime" to use in a way like "public void accept(final runtime Node::Stair inStair)" and "public void accept(final runtime Node::Door inDoor)" with a sematics like - if a client calls Method accept with a compile-time type of Node which has a runtime-type of Stair (Door respectively) then just dispatch to the specific method. It would be due to the compiler to require a programmer to implement a "default" Method whenever there's a runtime dispatch Method, to which a method call could be dispatched in case there's no specific method for any of the given runtime-types...

What a crazy idea...There must have been some kind of hallucinogen stuff in my coffee this morning. I see closures, I see no more checked exceptions, I see runtime-type dispatching, I see Java 7 that is no longer java...(sorry for the sarcasm, everything up to "++" is really meant as a constructive request ;-)
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Javalobby - Comments for "Dynamic visitor builder with closures"

I think those are generally

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