[Jython-dev] Simple java class import #2

[Oti <oh...@ya...>]

Hello Samuele,

please find below my second approach, hopefully closer to your
requirements.
I'd like to hear your comments before I flush the SF package manager
with more code.

This approach:
  - keeps the precedence 'python over java'
  - does not load any classes
  - IMHO is at the highest level possible 
  - passes test/test_import.py from the CPython 2.1.3 distribution
  - passes test/dynamic_import.py
  - allows package imports, too
  - enables fixing a bug

The idea is still the same:
If (for whatever reasons) a java package was neither scanned nor added
with sys.add_package(), we add it dynamically, after all other imports
failed.

There is a unittest attached (dynamic_import.py) which I expect to fail
with standard jython 2.1 (ImportError: no module named dynamic), while
it should succeed with the changes to imp.java and __builtin__.java
attached and described below.
In order to run this test, please add dynamic_import.jar to the
classpath, but do not add dynamic_extension.jar. Both jars have to be
in the same directory, though.

As a second step, you could disable the package scan (patch No. 525092;
safely leave the .py files untouched) and delete the cachedir. Again
the test should pass!

Thank you very much for your time reviewing this.
Best wishes,
Oti.



imp.java ( 'Release_2_1' = revision 2.59 )
------------------------------------------

- add the constant:
    String NO_MODULE_NAMED = "no module named ";
- replace the two "N/no module named" strings with this constant:
    throw Py.ImportError(NO_MODULE_NAMED + name);
- add the two methods isJavaClass() and isJavaPackage()


__builtin__.java ( 'Release_2_1' = revision 2.41 )
--------------------------------------------------

There are only changes to class ImportFunctions:
- in method __call__(), replace load() with dynamicLoad()
- add the methods:
    dynamicLoad(),
    findJavaPackage(),
    getFirstFrom(),
    eliminateNoneModules()




While developing the above I was able to fix a funny bug. Consider the
following situation:

1) somewhere on the classpath,
   there is aClass.class in package p1.p2:
     /p1
       +--  /p2
              +- aClass.class

2) somewhere on sys.path,
   there is aModule.py in directory /m1,
   and /m1 has an empty subdirectory /p1:
     /m1
       +--  aModule.py    contains 'from p1.p2 import aClass'
       +--  __init__.py   empty
       +--  /p1           empty directory

Now 'import m1.aModule' with the embedded 'from p1.p2 import aClass'
fails, while a plain 'from p1.p2 import aClass' succeeds.
There is a unittest attached (blocking_import.py) which exposes exactly
this situation. In order to run it, please copy javac.py from the
/Tools/jythonc directory to the /Lib directory. I expect it to fail
with standard jython 2.1 (ImportError: No module named p2), while it
should succeed with the fixes to PyJavaPackage.java described below.
However, I have no experience in importing java classes from sys.path,
so this might break some of your tests ?



PyJavaPackage.java ( 'Release_2_1' = revision 2.17 )
----------------------------------------------------

in method __findattr__(), replace:

  if (__mgr__.packageExists(__name__,name)) {
      __mgr__.notifyPackageImport(__name__,name);
      return addPackage(name);
  }

with

  if (__mgr__.packageExists(__name__,name)) {
    //check if it really is a java package
    String testPackage = "";
    if (__name__ != null && __name__.length() > 0)
      testPackage = __name__ + "." + name;
    else 
      testPackage = name;
    if (imp.isJavaPackage(testPackage)) {
      __mgr__.notifyPackageImport(__name__,name);
      return addPackage(name);
    } else {
      Py.writeDebug("import",
                    "'" + testPackage + "' is not a java package.");
    }
  }



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