Re: [Pyobjc-dev] Re: [ pyobjc-Bugs-679748 ] NSMutableString gets converted to Python string

[David E. <epp...@ic...>]

On 2/3/03 6:19 PM -0500 Bob Ippolito <bo...@re...> wrote:
>> Currently, because of the 7-bit possibility, if you want a unicode
>> string from a value s that came from the objc side, you need to call
>> unicode(s). I hope and assume that whatever happens with strings,
>> unicode(s) will still work.
>
> unicode(s) works for any str or unicode instance, or any instance that
> otherwise implements __str__ and/or __unicode__.  If it's a str or
> __str__ that has 8-bit characters, you have to specify an encoding.
> Optionally you may also specify a way to handle errors ('strict',
> 'ignore', or 'replace').

So I guess my point is that if NSStrings with 8-bit characters stopped 
being converted to unicodes automatically, an appropriate implementation of 
__unicode__ should be added.  It would be bad to go through __str__ and 
force an encoding to be specified explicitly, because an encoding is 
already determined for this kind of object.

On 2/4/03 12:24 AM +0100 Just van Rossum <ju...@le...> wrote:
>> Currently, because of the 7-bit possibility, if you want a unicode
>> string from a value s that came from the objc side, you need to call
>> unicode(s). I hope and assume that whatever happens with strings,
>> unicode(s) will still work.
>
> I'm curious: if the string is known to be 7-bit ascii, in what situation
> does an 8-bit string not work where a unicde string does?

I had some code of the form unicode(s).encode('utf8') because I thought it 
didn't make sense to encode something that wasn't already unicode.  But 
looking at it again, I guess encode works equally well on 7-bit strings...

> Btw. while peeking around I came across the thing Bill warned for:
> [NSString stringWithCString:] returns an instance of NSCFString, which
> is a subclass of -- tada -- NSMutableString. This doesn't mean it _is_
> mutable: I get an exception if I try. So _inheritance_ can't be used to
> determine mutability. Does anyone know off hand what can?

Any idea whether it reuses the storage of the C string, or copies it?
If it reuses it, it could be mutable by the C code...

--
David Eppstein       UC Irvine Dept. of Information & Computer Science
epp...@ic... http://www.ics.uci.edu/~eppstein/