🚀 go-pugleaf

[Sorry about the cross-post -- I felt this is a MAJOR issue that needs a
bit more visibility.]

I REALIZE THIS IS LONG, BUT PLEASE READ AS IT IS CONTAINS CRITICAL
INFO!!!
Note that this is _not_ a problem in the VAJ tool, but VAJ makes it a
bit too easy to accidently get this problem...


Enrique's post on ibm.software.vajava.language made me check a few
things out and I wanted to put a big warning out there on some coding
practices in case people didn't read that thread.

To sum up: IMPORT ON DEMAND IS DANGEROUS!

"Import on demand" is use of "*" in import statements. Whenever you use
a statement like:

  import a.b.*;

it tells the compiler "whenever you see a name you don't recognize, look
in package a.b".  If you have multiple import statements like this

  import a.b.*;
  import x.y.*;

and the unknown class exists in more than one of the listed packages,
the compiler reports an ambiguity conflict.


When I teach Java, I stress like crazy that you should _never_ use
import-on-demand in production code. I recommend you use it during
initial development for speed, but change it to explicit imports like

  import a.b.C;
  import x.y.Z;

before releasing.

THIS BECOMES CRITICAL FOR Java2!

In Java2, Sun has seen fit to add "List" to java.util as part of the
Collections support. This means that if your program has

  import java.util.*;
  import java.awt.*;

and you use "List" in your code, it will compile cleanly under JDK
1.1.x, but fail under the Java2 compiler. Think about the poor
maintenance programmer who has to figure out what to do...

Sun is doing similar API foolishness in 1.3, where they add Timer to
java.awt. This conflicts with Timer in javax.swing...

[Personally I feel this is idiotic for them to do -- they know damn well
that many people have

  import java.awt.*;
  import java.util.*;
  import javax.swing.*;

in their code. Not to mention the evil Date class in both java.util and
java.sql since 1.1... This just begs for problems when they allow
import-on-demand]

ACTION TO TAKE:
1) NEVER use import on demand in your code. Always use fully-qualified
imports
2) UNCHECK the "Add imports for fully qualified types from SmartGuides"
box in the Coding options if you're using VAJ 3.x. This adds
import-on-demand statements to your code.

Feel free to follow up or email me with questions or concerns...

--
-- Scott

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Scott Stanchfield    thetick@jguru.com    http://www.jGuru.com/thetick
jGuru Training by MageLang Institute      http://www.jGuru.com
VisualAge for Java Tips --> http://www.jGuru.com/thetick/visualage/tips
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