Re: [Jython-dev] jreload--it IS possible to reload a class in the same classloader

[Samuele P. <ped...@bl...>]

[oops, Finn has taken over my java classloaders guy role <wink>]

[myself]
> Have you tried that. Has he tried that?
>
> I have tried with:
>
> 1)
> java version "1.3.0"
> Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.0-C)
> Java HotSpot(TM) Client VM (build 1.3.0-C, mixed mode)

Does not work.


> 2)
> java version "1.1.7A"

Does work (see later).

> 3)
> Caricatore riga comandi Microsoft (R) per Java Versione 5.00.3802
> Copyright (C) Microsoft Corp 1996-2000. Tutti i diritti riservati.
> (It's jview, Versione is version)

Does not work.

> Funny, Funny.
> (To be honest I didn't need to try, jview not with standing)
>
Ok, I didn't know/remember about 2) but see later.


4) various sun jvm on solaris:
java version "1.1.8"
java version "1.1.6"

java version "1.3.1"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3.1-b24)
Java HotSpot(TM) Client VM (build 1.3.1-b24, mixed mode)

Does not work.

The 2nd edition of the JLS states a clear rule about class unloading
(btw class unloading is not mandatory but Jython works only on
jvms that implement it following the JLS rule). The rule is the one cited by
Finn:

http://java.sun.com/docs/books/jls/second_edition/html/execution.doc.html#74294

Btw the rule appeared in a set of Clarifications and Amendments to
The Java Language Specification (1st) edition:
http://java.sun.com/docs/books/jls/clarify.html

The clarifition about class unloading targets:
http://java.sun.com/docs/books/jls/first_edition/html/12.doc.html#44850

So: what he construes as > java 1.1 a feature:
- is a bug for a post clarication jvm (and indeed buggy jvms exist <wink>)
- a possible implementation feature for older jvms, but one portable code
cannot count on

So the guy should have known better (because even if at the time that was an
undocumented
feature it should have said whether he was talking about thin ice),

and we try our best to make informed and portable design decision.

[Btw java 1.4 offers class redefining features but through the debugging
interface
(not something that for  we can exploit as it is)
http://java.sun.com/j2se/1.4/docs/guide/jpda/enhancements.html#hotswap
]

regards, Samuele Pedroni.