Great! thanks for catching it up!
On Tuesday 12 September 2006 20:53, Saul Farber wrote:
> Hey all,
>
> Just had a thought while looking through the SDE dummy jars.
>
> Anywhere that one uses a construct like this:
>
> public static final int TYPE_SMALLINT = 0;
>
> For example, in SeColumnDefinition.java, I *think* java compiles the
> value of a public static final <primitive> right into the code. I.e. if
> there were two files like this:
>
> public ClassA {
> public static final int CONSTANT = 0;
> }
>
>
> and
>
> public ClassA {
> public static final int CONSTANT = 1;
> }
>
>
> And one compiled both of these class files into jars, and then compiled
> the following program twice:
>
>
> package org.depends.on.bad.java;
> public ClassAUser {
> public static void main(String[] args) {
> if (ClassA.CONSTANT == 0)
> System.out.println("ClassA.CONSTANT is Zero");
> }
> }
>
>
> The above "if" statement is calculated at COMPILE-TIME, not runtime, and
> so you'll get a fixed answer, no matter which ClassA you put on the
> classpath. Here's some sample output:
>
> [EMAIL PROTECTED] compilerTest $ javac -cp classAZERO.jar \
> ClassAUser.java
> [EMAIL PROTECTED] compilerTest $ java -cp classAZERO.jar:. \
> ClassAUser ClassA.CONSTANT is Zero
> [EMAIL PROTECTED] compilerTest $ java -cp classAONE.jar:. \ ClassAUser
> ClassA.CONSTANT is Zero
> [EMAIL PROTECTED] compilerTest $
> [EMAIL PROTECTED] compilerTest $
> [EMAIL PROTECTED] compilerTest $ javac -cp classAONE.jar \
> ClassAUser.java
> [EMAIL PROTECTED] compilerTest $ java -cp classAZERO.jar:. \
> ClassAUser [EMAIL PROTECTED] compilerTest $ java -cp classAONE.jar:. \
> ClassAUser [EMAIL PROTECTED] compilerTest $
>
>
> Hmmm...that's bad. This means that if we don't have the "public static
> final int TYPE_SHAPE" set to exactly the same integer as the SDE API, we
> won't be able to do drop-in replacement. Things will compile, but
> anything based on a public constant (mostly shape type discovery and
> such) won't work correctly unless one *compiles* the code with the SDE
> jars.
>
>
> I wonder if I can get around this by changing the variables from public
> static final to just "public static".
>
> Then we might trick the compiler into not doing compile-time evaluation
> of those constants.
>
> Let me check...
>
> Yes! It works.
>
> Ok, so I'd suggest that we remove the "final" modifier from all the
> public static constants in the SDE Java API dummy sources. Otherwise
> stuff won't really work the way we want it to!
>
>
> --saul
>
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--
Gabriel Roldán ([EMAIL PROTECTED])
Axios Engineering (http://www.axios.es)
Tel. +34 944 41 63 84
Fax. +34 944 41 64 90
-------------------------------------------------------------------------
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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