[Pyobjc-dev] A question of concience

[Ronald O. <ous...@ci...>]

In a private conversation Dan Grassi mentioned that methods like the 
one below are transformed into Python methods in an unexpected way. 
Specifically:

	-(void)getNumberOfRows:(int*)rowCount columns:(int*)columnCount; // 
both are output parameters

is translated into
	getNumberOfRows_columns_(self) -> (None, rowCount, columnCount)

He expected that the result would be (rowCount, columnCount).

I think he has a point. The current translation is the result of 
applying the basic rule a little too strictly. The basic rule says: The 
return value of methods with output arguments is a tuple containing the 
original return value, followed by the values of all output arguments 
in order. A return type of 'void' is usually translated into a method 
returning None, and therefore the return value for the method mentioned 
above is a tuple with None as its first element (the original return 
value).

Just ignoring the original return value if this is always void would be 
more usefull, as a method returning void is a method that does *not* 
return a value when viewed as an Objective-C method. This would make 
the translation of getNumberOfRows:columns: more natural.

There is one problem with this change: backward compatibility. If we'd 
apply this change, we might break code that currently uses methods like 
getNumberOfRows:columns:. The current users might also use code that 
wouldn't break, like this:
	rows, cols = obj.getNumberOfRows_columns_()[1:]

I'd rather not break backward compatibility, but this change would 
increase the useability of PyObjC. Any opinions?

Ronald