[lang][proposal] SystemUtils property out of sync problem; add se t methods.

[Gary Gregory <gg...@seagullsw.com>]

Hello,

Context: I am writing some unit tests for our product that require system
properties (like java.ext.dirs) to be temporarily fiddled with. Now my code
looks like this:

    public void testJavaExtDirDoesNotExist() {
        String saveJavaExtDirs = SystemUtils.JAVA_EXT_DIRS;
        try {
            String testJavaExtDirs = "...";
            System.setProperty("java.ext.dirs", testJavaExtDirs);
            // The real test starts here...
        } finally {
            System.setProperty("java.ext.dirs", saveJavaExtDirs);
        }
    }

Issue #1: Add SystemUtils.setX?
--------

Instead of:

System.setProperty("java.ext.dirs", testJavaExtDirs);

I wonder if this would be better:

SystemUtils.setJavaExtDirs(testJavaExtDirs);

Seems nicer, yes?

Issue #2: SystemUtils out of sync.
--------

As soon you do:

System.setProperty("java.ext.dirs", testJavaExtDirs);

Then SystemUtils.JAVA_EXT_DIRS lies.

Proposal 2a:
At least, the Javadoc has to be updated to something nasty like: "The value
of this constant is set when this class is first loaded."

Proposal 2b:
Add SystemUtils.getJavaExtDirs() and other APIs which do not cache and make
JAVA_EXT_DIRS and others use such APIs.

Proposal 3b: 
Add constants for the property names like: JAVA_EXT_DIRS_KEY =
"java.ext.dirs".

?
Gary

Re: [lang][proposal] SystemUtils property out of sync problem; add set methods.

[Stephen Colebourne <sc...@btopenworld.com>]

My gut feeling is that this is an unusual case. Certainly, adding javadoc to
say that the values are set when the class is class loaded is a good idea.

Extra set/get methods are troublesome though, and I don't really want to
expose more constants for the extra keys.

Do people really change these values? (other than in tests, which kinda
don't count...)

Stephen

From: "Gary Gregory" <gg...@seagullsw.com>
> Context: I am writing some unit tests for our product that require system
> properties (like java.ext.dirs) to be temporarily fiddled with. Now my
code
> looks like this:
>
>     public void testJavaExtDirDoesNotExist() {
>         String saveJavaExtDirs = SystemUtils.JAVA_EXT_DIRS;
>         try {
>             String testJavaExtDirs = "...";
>             System.setProperty("java.ext.dirs", testJavaExtDirs);
>             // The real test starts here...
>         } finally {
>             System.setProperty("java.ext.dirs", saveJavaExtDirs);
>         }
>     }
>
> Issue #1: Add SystemUtils.setX?
> --------
>
> Instead of:
>
> System.setProperty("java.ext.dirs", testJavaExtDirs);
>
> I wonder if this would be better:
>
> SystemUtils.setJavaExtDirs(testJavaExtDirs);
>
> Seems nicer, yes?
>
> Issue #2: SystemUtils out of sync.
> --------
>
> As soon you do:
>
> System.setProperty("java.ext.dirs", testJavaExtDirs);
>
> Then SystemUtils.JAVA_EXT_DIRS lies.
>
> Proposal 2a:
> At least, the Javadoc has to be updated to something nasty like: "The
value
> of this constant is set when this class is first loaded."
>
> Proposal 2b:
> Add SystemUtils.getJavaExtDirs() and other APIs which do not cache and
make
> JAVA_EXT_DIRS and others use such APIs.
>
> Proposal 3b:
> Add constants for the property names like: JAVA_EXT_DIRS_KEY =
> "java.ext.dirs".
>
> ?
> Gary
>
>


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