Re: [Pyobjc-dev] NSString & mutability

[Just v. R. <ju...@le...>]

bb...@ma... wrote:

> Nice hack, but....
> 
> What about all the code that might return a mutable string depending
> on how the developer exercises the API?  Are you willing to assume
> that every getter and setter that internally makes a immutable copy
> of the set string value?  i.e. that...
> 
> .... [fooObject setMyNameIs: someRandomMutableString]; return
> [fooObject myNameIs] ....
> 
> .... that -myNameIs will return an immutable string?

I'm totally willing to accept a surprise like that. I don't even see the
problem when using such an API from Python: you call
fooObject.setMyNameIs_() with a Python string, you call myNameIs() and
get a Python string. Same string, different id. No problem in Python.

Can you please give an example of an _actual_ problem? I'll have a go
myself:

Let's assume the API does the reverse: it takes an immutable string, yet
returns its internal mutable copy, although myNameIs is declared to
return an NSString. Now there _is_ a surprise: instead of a 100%
equivalent string we get an NSMutableString instance. Ok, a surprise,
but is it so bad? If the object internally uses a mutable string, it's
likely that this is clear from the nature of the object (eg. it's some
sort of editor for the string). So I still think such a surprise will be
rare.

> See this message -- it is still quite relevant.  Mike Ferris is one
> of the guys who helped write the AppKit and Project Builder.
> 
> http://www.omnigroup.com/mailman/archive/macosx-dev/2000-May/001886.
> html

It's an example of NSArray, which we don't convert, so we live
dangerously anyway in PyObjC as we don't even have the hint from the
header that we _shouldn't_ mutate even if it is mutable.

Just