Troubleshooting Migration from Jython Version 2.1 to 2.5.3

• Error message: TypeError: int argument required
• Possible cause: Using string formatting to decimal integer from string variable containing integer data.

• Problematic Jython 2.1 code:

  variable = "43"
print "%d" % variable

• Correct Jython 2.5.3 code:

  variable = "43"
print "%s" % variable

  or

  variable = "43"
print "%d" % int(variable)
  

The code below may not work correctly if input contains unicode strings:

• Problematic Jython 2.1 code: isinstance(unicodeStringVariable,'')

• Correct Jython 2.5.3 code: isinstance(unicodeStringVariable,basestring)

  The comparison should be done with basestring to test whether an object is an instance of str or unicode.

• Error Message:
SyntaxError: Non-ASCII character in file 'x', , but no encoding declared; see http://www.python.org/peps/pep-0263.html for details

• Correct Jython 2.5.3 code: (add this to the first line in the file)

  # coding: utf-8

• Error message:
  AttributeError: 'module' object has no attribute 'sub_package_name'
• Possible cause: A sub-package is imported without explicitly specifying the name of sub-package in the import statement.

• Problematic Jython 2.1 code:

  import a
print dir(a.b)

  The sub-package is not explicitly imported.

• Correct Jython 2.5.3 code:

  import a.b

  or

  from a import b

Starting from Jython 2.2, the __iter__ method is used to loop over a collection in the scope of a for-in block. The iterator should implement the next method, returning an appropriate element or throw the StopIteration error if it reached the end of the collection. If the __iter__ method is not implemented, the getitem method is used instead.

• Jython 2.1 method for raising exceptions is obsolete:
  raise Exception, 'Failed getting contents of file'
• Recommended Jython 2.5.3 method for raising exceptions:
  raise Exception('Failed getting contents of file')