LISTSERV mailing list manager LISTSERV 16.0

Help for TEAM-ADA Archives


TEAM-ADA Archives

TEAM-ADA Archives


TEAM-ADA@LISTSERV.ACM.ORG


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

TEAM-ADA Home

TEAM-ADA Home

TEAM-ADA  September 1998

TEAM-ADA September 1998

Subject:

Re: Clarification: Ada/Java

From:

Geoff Bull <[log in to unmask]>

Reply-To:

Geoff Bull <[log in to unmask]>

Date:

Fri, 18 Sep 1998 12:15:16 +1000

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (185 lines)

W. Wesley Groleau x4923 wrote:

> > The "Purity" Measure
> > ====================
>
> > Conclusion: Java and Ada aren't really so far apart here after all. But I
> > still give Java a slight edge on the "purity" scale. If "purity" sounds too
> > subjective (and thus irrelevant) call it "consistency and ease of use."

I have seen an argument that Ada is not OO because it uses syntax like

method_name (object_name, args ...)  instead of   object_name.method_name(args ...)


> > Dynamic Class Loading
> > =====================
> >
>
> > Well, help me here. In Java, I can create an object at run-time whose class
> > didn't even exist at compile time. For example, I can prompt the user for a
> > String and then use that String as an argument in the Class.forName method.
> > Once I have the the Class object, I can call its newInstance method. I believe
> > the technical term for this is "Way Cool". That seems like a language feature
> > to me but I realize I may be missing something.

I have seen this sort of "way cool" feature with dynamic linking to shared objects
longbefore
Java was even a twinkle in James Gosling's eye.
Admittedly Java's mechanism is simple to use.

> > Wacky C Syntax I
> > ================
> >

I suspect that Java would not have been successful if it didn't have the smell of C around
it.So, although I hate the syntax, I believe the language designers made a correct
decision.

Java culture seems to generate more understandable identifier names than C.I can't
understand though why white space and underscoring tends to be
used very little to improve readability.

Case sensitivity is not to my taste.
e.g. java.awt.event and java.awt.Event are two different things (a package and a class)

Perhaps a good compromise would have been to enforce case consistency,
and disallow identifiers that differ only in case.


> > Specifications compilable before implementation
> > ===============================================

It is very easy to accidentally change specifications in Java.

> > Enumerated types, non-Zero-Based Array Indices
> > ==============================================

Wonder why they left them out?

> > Object Equality
> > ===============

Personal I find writing "if (a.equals (b))" instead of "if (a == b)" ugly

Numerics Support
=============
Java requirement that answers be exactly the same on all platforms is a definite problem.
E.g. Java won't allow you to take advantage of 80 bit fp on intel platforms.
       Won't allow use of multiply-add instructions that might carry more precision
through.


Representation Specification
===================
The bit bashing that I had to do for one Java project made it very hard to understand
and a pain to change - it would have been fine, except I knew there was a better way.

> > Operator overloading
> > ====================
>  Java takes away a valuable capability because programmers
> > >      abused it.

Trouble with C++ was it allowed overloading of ALL operators and has a wide defination of
operator.Reading code that has () or [] overloaded generally leads to very slow
understanding.

Overloading on Return Type
===================
Even though return type is included in signature two methods with same name
must differ by more than just the return type. This leads to swags of methods that have
the return
type encode in the name.

> > Access-to-subprogram that is fully type safe and nesting safe
> > =============================================================.
>
> Java "rejected access-to-subprogram because it wasn't safe." (not in those terms)

You can get an inefficient form, if you use reflection - can't remember if that is safe.

> > Tasking
> > =======
> >
> > The usual points...

What are these?

I find the fact that Thread.setPriority () is not guarantted to have any effect truly
amazing.
I have one Java program that absolutely depends on thread priority to work - I decided
to sacrifice portability, rather than waste time figuring out a complicated work around.

> > The OOP inheritance mechanism is independent of the encapsulation mechanism
> > ===========================================================================
>
> > > Java classes cannot share private data like two or more Ada types in one
> > > Ada package.  In Java, the methods and instance variables are encapsulated
> > > within the class, which corresponds to ONE Ada type as well as ONE Ada
> > > package.

You can get a similar effect using inner classes.Unfortunately,  inner classes require an
instance of the outer class to exist before you can use them.
E.g. a class cannot have a static instance of an inner class.
Also, instances of inner classes can only exist within their outer class (am I correct on
this?)

Generics /Templates
==============
Lack of this facility leads to code copying, which reduces productivity of both
initial coding and maintenance.

Others
=====
Only unsigned type is char - this is a huge pain when tou really need to do unsigned
arithmetic.

Only form of abstraction requires heap allocation - ridiculous for class Complex. This
also deters the performance conscious from using any abstraction.

Bounds checking is limited to arrays only - I have to roll my own for anything else.
Even integer arithmetic silently overflows.

Loose typing of primitives: e.g.
long foo = 0x00000000ffffffff;  // surpise! foo == -1

no package renaming - witness current problems with change of name of com.sun.java.swing
to javax.swing. Also, lack of this leads to importing everything and subsequent
readability pronlems.

no default values for arguments

no named association of arguments - non Ada programmers don't seem to care about this
though.

no explicit elaboration contol - this makes some initialisation issues non-obvious.

interfacing to other languages is very messy (with JNI)

easy to make typos change meaning rather than create illegal program.

performance - BEST I can get out of Java (with JIT compiler) is half as fast as Ada or C.
( I did some tests to debunk claims that Java was faster than C at numerics,
I don't know what code the original claim was for, but it doesn't work for matrix
multiplies).
At least the Java version of my mini benchmark worked first go, which is more than you can
say for the C.


Lastly, I am laughed at everytime I mention Ada:
Ada is HUGE, Ada takes too long to learn, Ada is too verbose, Ada takes too long to write,

Ada is ugly, Ada projects frequently fail, Ada is slow, Ada is not OO, nobody uses Ada,
if we learn Ada we won't get a job anywhere else, etc, etc.

So, I mostly program in Java, which I consider to be an inferior languagein many respects
(to Ada),
although it is generally a great improvement on C/C++.

Personally, I think we should take Ada, call it something else, and claim we have just
invented
the next great thing.

cheers
gb

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

December 2017
November 2017
October 2017
September 2017
June 2017
May 2017
April 2017
January 2017
December 2016
November 2016
October 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
December 2010
November 2010
October 2010
September 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
June 2007
May 2007
March 2007
February 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
October 2005
August 2005
July 2005
June 2005
May 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004
July 2004
June 2004
May 2004
March 2004
February 2004
January 2004
December 2003
November 2003
October 2003
September 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003
December 2002
November 2002
October 2002
September 2002
August 2002
July 2002
June 2002
May 2002
April 2002
March 2002
February 2002
December 2001
November 2001
October 2001
September 2001
August 2001
July 2001
June 2001
May 2001
April 2001
March 2001
February 2001
January 2001
December 2000
November 2000
October 2000
September 2000
August 2000
July 2000
June 2000
May 2000
April 2000
March 2000
February 2000
January 2000
December 1999
November 1999
October 1999
September 1999
August 1999
July 1999
June 1999
May 1999
April 1999
March 1999
February 1999
January 1999
December 1998
November 1998
October 1998
September 1998
August 1998
July 1998
June 1998
May 1998
April 1998
March 1998
February 1998
January 1998
December 1997
November 1997
October 1997
September 1997
August 1997
July 1997
June 1997
May 1997
April 1997
March 1997
February 1997
January 1997
December 1996
November 1996
October 1996

ATOM RSS1 RSS2



LISTSERV.ACM.ORG

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager