On Wed, 2006-06-21 at 13:39 +0200, Jeroen Frijters wrote: > Hi, > > Now that builder is using a new version of ecj, the generics branch no > longer compiled due to a cast bug. I checked in a fix. > > Regards, > Jeroen > > 2006-06-21 Jeroen Frijters <[EMAIL PROTECTED]> > > * java/util/Collections (entrySet): Fixed compile error.
It's a horrible way to fix it, but then most of the things about how Java has implemented these things is. For those who don't know, the 'fix' is basically to insert a cast to a raw type prior to the conversion to Class<Map.Entry<K,V>>. The result is that instead of applying a capture conversion (where the parameters of a type are converted, G<T_1...T_n> to G<S_1...S_n>, which requires either exact type equality or wildcards - 5.1.10 in the 3rd edition of the language spec.), we remove the type parameters, creating a raw type. An unchecked conversion (5.1.9) then converts the raw type back to a parameterized type, which only results in an unchecked warning. Raw types are basically legacy versions of types that are now parameterized (e.g. List as opposed to List<T>) and are required so that every Java program doesn't break with the new type system. The problem with how generics are implemented is that they are fine when we are just showing people nice examples like 'oooh, you can get things from your list without having to cast' but are soon as you get to any point where the things have to interact with stuff that isn't typed that way, things go mad. This happens all over the Java API, and especially in the collections classes. The problems arise from bending over backwards to support Java 1.4 and below, and IMO, they pretty much ruin the advantages of having a more advanced type system. Cheers, -- Andrew :-) Please avoid sending me Microsoft Office (e.g. Word, PowerPoint) attachments. See http://www.fsf.org/philosophy/no-word-attachments.html If you use Microsoft Office, support movement towards the end of vendor lock-in: http://opendocumentfellowship.org/petition/ "Value your freedom, or you will lose it, teaches history. `Don't bother us with politics' respond those who don't want to learn." -- Richard Stallman Escape the Java Trap with GNU Classpath! http://www.gnu.org/philosophy/java-trap.html public class gcj extends Freedom implements Java { ... }
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