On 25.03.2009, at 10:13, Mark Engelberg wrote: > 1. Structs don't inherently have a type. If you want to dispatch on > type (a common use-case), you have to make a constructor that inserts > the type information as part of the struct. Some have expressed
And/or in the metadata. > concern that it may be too easy for this "type information" to be > altered, or worse, the data could be "changed" or "removed" in a way > that makes the struct inconsistent with the type label it carries > around. I am one of those who have expressed concerns, but I must also say that until now I have not encountered such a problem in real life. I have come to the conclusion that interfaces and types work differently in Clojure than in other languages that most of us are more familiar with. So perhaps we are expecting problems that really aren't there once you figure out how to do it "right". > 2. No way to call "next-method" or "super", which limits the ability > to reuse related methods. Again, I'd like to see a real-life situation where this is an issue. > 3. The dispatch mechanism requires a lot of explicit prefer-methods, > or else it may be hard to guarantee you won't get a run-time error > from a situation the dispatch system considers ambiguous. This also And there as well. > makes code less extensible because to add a method, you must know > about all the other methods that have been implemented in order to > insert all the appropriate preferences. This would only be an issue in complex hierarchies. As long as each library just adds its types to a hierarchy and implements methods for them, there is no problem. That's why I'd like to see the real-life situation where there is one. Konrad. --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Clojure" group. To post to this group, send email to clojure@googlegroups.com To unsubscribe from this group, send email to clojure+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/clojure?hl=en -~----------~----~----~----~------~----~------~--~---
