[Pyobjc-dev] More fun with NSTableView

[Mitch C. <mit...@ea...>]

Hi,

[Python 2.3b1, PyObjC from CVS, updated less than five minutes ago.]

I'm trying to figure out how to supply instances of user-defined Python  
classes
as values for display in an NSTableView, and am stumped again.

In the end I'd like to be able to supply one of these Python objects to  
a subclass
of NSCell which extracts rendering information (say, a list of polygon  
vertices)
from the Python objects.

I thought I'd start simple:  define a Python "value" class which knows  
how
to represent itself as a string.  But I didn't start simply enough.

Suppose the value class looks like this:

class CustomCellValue(NSObject):
     """Provides the value for a custom cell."""

Suppose the table's data source does this:
     def tableView_objectValueForTableColumn_row_(self, aTableView,  
aTableColumn, rowIndex):
         """Get the object value for a table cell."""
         ident = aTableColumn.identifier()
         result = "%s %s" % (ident, rowIndex)
         if ident == "custom_column":
             # Trying to create a simple Python object which is  
accessible
             # from OC.
             result = CustomCellValue.alloc().init()
         return result

When I run the program, I get the following error on the first rendering
attempt.

2003-06-03 21:44:02.624 CustomTableCell[15987] *** -[CustomCellValue  
copyWithZone:]: selector not recognized
Traceback (most recent call last):
   File  
"/Users/mitchchapman/projects/br/Prototypes/CustomTableCell/build/ 
CustomTableCell.app/Contents/Resources/__main__.py", line 24, in ?
     sys.exit(AppKit.NSApplicationMain(sys.argv))
ValueError: NSInvalidArgumentException - *** -[CustomCellValue  
copyWithZone:]: selector not recognized

This looks peculiar because NSObject provides a valid implementation
of +copyWithZone:, and the docs say you should not override it.

I have verified that my instance actually gets created without incident.
It just doesn't seem to understand copyWithZone:.

Thanks again for clues.

--
Mitch