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From: Lew <noone@lewscanon.com>
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Subject: Re: Java vs C++
Date: Tue, 08 Feb 2011 07:53:33 -0500
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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 fenêtre.
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