Re: [Pyobjc-dev] NSAttributedString returns a tuple, not an NSAttributedString

[Diez B. R. <de...@we...>]

On Oct 17, 2010, at 10:56 AM, Michael Thon wrote:

> Hello -  I am trying PyObjC for the first time and I discovered something that I don't understand.  If I initialize an NSAttributedString like this:
> 
> content = NSAttributedString.alloc().initWithPath_documentAttributes_(a_path, None)
> 
> Then content contains a tuple, not an NSAttributedString.  If I initialize is like this:
> 
> content = NSAttributedString.alloc()
> a_tuple = content.initWithPath_documentAttributes_(a_path, None)
> 
> Then content contains an attributed string from the contents of the file, and a_tuple contains a tuple.  On the other hand NSAttributedString.alloc().init()
> returns an instance of NSAttributedString, as expected.  So, apparently initWithPath_documentAttributes_() returns a tuple instead of an instance of NSAttributedString.  My question is, is this by design (and thus, there is something about PyObjC that I don't understand) or is it a bug? 

It's by design. Pay close attention to the argument list: the parameter you pass as None is a pointer to a pointer. Which means it is an out-parameter. Python lacks the semantics for this, so instead, signatures of that kind are implemented by returning the value as tuple.

Diez