(Pdb) myclass
MyClass( 0, 0, 'A string', 123.45)
(Pdb) copy.copy(myclass)
*** TypeError: TypeError('__new__() takes at least 4 arguments (2 given)',)I see 4 arguments (actually, 5 because Python is passing cls invisibly to __new__). Does anyone have an idea what is going on here? I have not defined __new__ in MyClass above. I can make the problem go away on one platform by defining __new__ as return MyClass(self, self.arg1, self.arg2, self.arg3) but I understand that return value to be the default, so I don't see why defining that method makes a difference. On another platform, that definition causes a different problem (I seem to be getting None as the return value of the copy in some cases). By the way, I have simplified somewhat the code in the explanation. In case it might matter, know that there are actually two classes that exhibit this problem. In one, there is actually a fourth argument in the __new__ method that has a default value (the float above), which is why the error message says that __new__ expects *at least* 4 arguments. In the other, the last argument is a parg collector. I have also had trouble pickling these classes. I surmise that pickle uses copy. -- Jeffrey Barish -- http://mail.python.org/mailman/listinfo/python-list
