Additional method on Stream (original) (raw)

Remi Forax forax at univ-mlv.fr
Sat May 2 14:41:31 UTC 2015


On 04/28/2015 03:05 PM, Paul Sandoz wrote:

[...]

I do understand the desire to control methods, but API design isn't just about minimalism, it is also about meeting common use cases in a natural way. The parallel is of course a standard if (obj instanceof Foo) statement in Java, where developers often curse that they have to additionally cast obj after the check. I believe Ceylon might also do contextual type narrowing. I dunno how easy it would to modify the Java language and javac to do similar things. A separate discussion to be had...

I think this was discussed on the coin project mailing list when talking about the precise re-throw of exception. The main issue is that a more precise type will select another overload than the one that javac currently select:

class A {} class B extends A {} class Bar { void foo(A a) { ... } void foo(B b) { ... } }

Let suppose we have this code: A a = ... if (a instanceof B) { foo(a); }

without narrowing, it will call foo(A), with narrowing, it will call foo(B).

Rémi



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