[1738] in java-interest
A few queries...
daemon@ATHENA.MIT.EDU (Llew Mason)
Fri Sep 15 12:41:25 1995
From: Llew Mason <mason_l@ee.uwa.edu.au>
To: "java-interest@java.sun.com" <java-interest@java.sun.com>
Date: Fri, 15 Sep 1995 21:35:04 +-800
Hi all,
I've been evaluating Java for the past few days and have a few queries =
on the language. (keep in mind that I have been using the NT 1.0a3 =
release and haven't seen the development kit) Please correct me if =
anything I have stated below is incorrect.
1) Pass-by-value vs pass-by-reference vs pass-by-const-reference
As far as I could tell this wasn't discussed in any of the provided =
documention. Java currently passes class arguments by non-const =
reference. I assume that the currently reserved const keyword will =
allow argument passing by const reference eventually. I can't see any =
point in Java ever providing pass-by-value support.
Why was argument passing by non-const reference chosen as the default? =
This seems to be a dangerous practice and inconsistent with Java's =
efforts at removing unsafe practices from the C++ language. (removal of =
pointers was a good start)
2) Meta-classes (template classes for those unfortunate C++ people)
There seems to be no way to implement meta-classes within Java. The =
interface mechanism allows for class methods to operate on any class =
which implements a particular interface, but cannot guarantee the =
homogeneity of instantiated classes. This makes usage of classes like =
Vector unsafe (not to mention inelegant) since all elements need to be =
typecast to the required type upon extraction.
3) Operator overloading
Why was this omitted from the Java language? This is one of the =
'neat' features of languages like C++. (although I'd prefer overloaded =
operator support like that provided by ML, where new operators can be =
defined and operator precedence can be redefined)
Web applets would rarely require operator overloading, but if Java is =
intended to be used for any serious development where mathematical =
classes are required then it quickly becomes unwieldy.
Specifying complex numbers as z.mul(z).plus(c) for Mandelbrot =
generation is ugly compared with z =3D z * z + c. Reading code =
consisting of operations on complex number, vector, matrix and tensor =
classes becomes almost impossible without overloaded operators being =
defined for these classes.
I admit that operator overloading can be abused, but then so can =
function naming.
4) AWT class package DisplayItem class
Why is the DisplayItem class inherited from the Browser.Observable =
class?
I would think that the base GUI package should not take inheritance from =
specific application classes. (Like the HotJava application)
Overall I'm quite impressed with what I've seen of Java. With native =
machine-code compiler support, meta-classes and operator overloading I =
see no reason why Java couldn't become as popular as C++.
Llew Mason
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