Re: [Pyobjc-dev] Auto bridging instances by conversion

[<bb...@ma...>]

On Tuesday, Feb 4, 2003, at 04:01 US/Eastern, Just van Rossum wrote:
> Sure, eg. in Python this happens with exceptions. However we're not
> talking about arbitrary objects, but about real basic immutable types
> (strings and numbers). I claim that any code in which the id of an
> NSNumber or NSString is important is seriously broken.

That claim is faulty.

There are many situations where the type of the object is totally 
irrelevant to the local implementation.  That is, as far as the 
implementation is concerned, everything is an (NSObject*) and the only 
important piece of information is the id-- the self pointer-- of that 
object.    As Ronald indicated, this situation arises outside of 
various random performance hacks-- NSMapTables and the underlying CF* 
types are often used to map instances to other instances, regardless of 
type, as a part of object graph maintenance.

By assuming otherwise, the bridge will cause very subtle, but very 
ugly, problems in many situations where the developer is going to be 
mighty surprised that it didn't "just work".   We already have that 
situation with the string conversions that are happening now.

b.bum