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From: v_borchert@despammed.com (Volker Borchert)
Newsgroups: comp.lang.java.programmer
Subject: Re: Alternatives languages on the JVM: which one or is there no alternative?
Date: 29 Nov 2013 23:37:56 GMT
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Joshua Cranmer ???? wrote:

> And you think multiple inheritance has no costs?

No.

> 2. Offsets to a particular named field are dependent on object 
> instances, not on classes/class hierarchies.
> 3. Casting up or down a tree requires recomputing offsets on a 
> per-object instance basis, not a per-class basis.

If they had spent the time wasted on yet another GUI framwork on
these... After all, that's what JIT is good at, isn't it?

> inheritance, at least as 
> Java is concerned, is meant to model an "is-a" relationship, not a 
> "has-a" relationship.

I know. And IMO this holds true generally, not only for Java.

I admit that in my Cache<K,V> example  you could argue that the Entry
_has_ a WeakReference<V> rather than _being_ one. But then, being-a
WeakReference<V> is very similar to weakly-having-a V, isn't it?

> Since inheritance is an indelible part of the 
> public contract of a class in Java,

Another shortcoming of Java, but not necessarily of the JVM - lack of
nonpublic inheritance.

> Let the JIT and the optimizer work through the overhead;

They can't work through the extra memory required for the extra object
needed for aggregation.

> premature optimization, after all, is the root of all evil.

+1

-- 

"I'm a doctor, not a mechanic." Dr Leonard McCoy <mccoy@ncc1701.starfleet.fed>
"I'm a mechanic, not a doctor." Volker Borchert  <v_borchert@despammed.com>