Re: Java vs C++

From:

Lew <noone@lewscanon.com>

Newsgroups:

comp.lang.java.programmer

Date:

Tue, 08 Feb 2011 07:53:33 -0500

Message-ID:

<iirebq$9k4$1@news.albasani.net>

Andreas Leitgeb wrote:

The "problem" about type-erasure is over-rated.

Suppose, an instance created so: Object o = new ArrayList<String>();
actually "knew" that it was an ArrayList of Strings (and not just
that it was an ArrayList, as it does now).
Then you would get a *runtime*-Error, if you tried to cast "o" to
ArrayList<Integer>, later. But generics aren't about runtime errors.
They are about being able to prevent some runtime-errors, by turning
them into compile-time errors. So, giving *still runtime*-errors for
casting between generic types of incompatible parametrizations is only
little win over giving runtime-errors on element-use.

I'm very glad you made that point. I am glad we have type erasure in Java.
It forces you to deal with type assertions at compile time.

The problem with reifiable types is that it's too easy to do a half-assed job
of your type analysis, thus resulting in the runtime errors to which Andreas
alludes. Besides, all you need to do to get runtime typing is to include a
runtime type token as a final member of your class and Bob's your uncle. Like
so much else in Java, that just means you have to *think* and act for
yourself, and type a few extra lines of code. Don't sprain your finger with
that extra typing, whiners!

--
Lew
Ceci n'est pas une fen??tre.
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