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Showing posts from December, 2006

Local Builder Pattern Broken in Java?

Time and again, when I want to break up a longish Java method into smaller parts, I find myself wishing back the by-reference parameters and access to surrounding local procedure variables of Pascal. Now, I know that the discipline of trying to always pass all required arguments explicitly, and to not rely on changes to by-ref params is often helpful. Nevertheless, sometimes it gets in the way. One fairly clutter free approach to get Pascal's features back goes like this: public interface LocalBuilder { T build(); } and then: public MyClass computeIt() { new LocalBuilder () { final int input1 = ...; final int input2 = ...; int state1 = ...; int state2 = ...; public MyClass build() { stepOne(); stepTwo(); return result(); } private void stepOne() { ... } private void stepTwo() { ... } private MyClass result() { ... } }.build(); } While this basically works, it has a few problems: Exceptions thrown by build() must be declared already on