Re: java question?

[Noel Yap]

--- pootle monster <address@hidden> wrote:
> 
> >
> >I'm not sure, but you might be able to use the
> >ClassLoader and reflection to achieve this although
> I
> >suppose you'll want this info before run-time. 
> OTOH,
> >in order to build a set of classes used by the
> >application (and not have any false negatives),
> using
> >the ClassLoader will give you exactly that set.
> >
> 
> Im interested this but not sure how to go about it.
> can you give me a few pointers
> 
> Id want to get the info on calling the main with a
> -version param

You'll have to find help elsewhere since I've never
done it myself.

> >From experience, if you do it the way you want,
> you'll
> >have to contend with a lot of version-to-version
> >dependency issues (eg which versions of class X
> will
> >work with which versions of class Y?).  It's much
> >easier to deal with these issues from a
> larger-grained
> >perspective (eg which versions of
> >component/package/module X will work with which
> >versions of component/package/module Y).
> 
> 
> the problem is that I have loads of classes in many
> different packages
> each applications individual classes are in a
> seperate package but they use 
> many of the same util classes
> I often update my util classes, always keeping the
> same interfaces, but mabe 
> adding others.
> If I update one of these I do not want to put a new
> 'tag' on the 
> applications that use it for many reasons:

I agree.  You'll need to keep track of library version
dependencies some other way.  IOW, when it comes to
using your utils jar file, treat them the way you
would treat the JDK jar files.

> 1: It wont change the application

I agree.

> 2: I would have to look at every class in every
> application to see if it 
> used the util class, and so then update it with a
> new tag or not

If you had a release cycle for the utils jar file, you
will need to know which applications used it and test
those for each new release of the utils jar file.

Let's say you had several applications that worked
with each other (thereby comprising a system).  Would
you then tag all the applications each time one of
them was changed?  I would think not, but rather, you
would track version dependencies through some other
means (possibly documentation).  It's the same with
library dependencies of applications.

> 3: would not the util class have to have a different
> tag for each 
> application that used it?(they might start stacking
> up)

Again, not if you track these kinds of dependencies
from outside the version control tool.

OTOH, I think some CMs use ClearCase in this way
(versioning, not only third-party libraries, but tools
(eg compilers) as well).  This may be feasible to do
in ClearCase.  It is not in CVS.

> 4: all my applications are packaged in one jar and
> so will use the util 
> class there not just the one when the application
> was last 'tagged'

Again, this is a release issue, not a version control
issue.

Noel


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