Re: [Pyobjc-dev] Bridging NS and CF classes

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

On Thursday, Jan 9, 2003, at 17:24 US/Eastern, Jack Jansen wrote:
> But that doesn't really matter: the PyObjC code could look at the type 
> of the Python object and pass any CoreFoundation object as the 
> corresponding NS object still.

Ideally, we could automatically determine that there is a 
representation of the given object / type ref on the other side of the 
bridge.

Two separate problems -- end result, a single message to return the 
'other' type.   Two slightly different problems, I think.

I have asked if there is a transparent way of determining if a 
particular type/object is bridged on cocoa-dev.  Hopefully, someone 
there will cough up a clean and easy solution. :-)

NS -> CF:

     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([NSArray array])));
     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([NSDictionary 
dictionary])));
     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([NSMutableArray 
array])));
     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([NSBundle 
mainBundle])));
     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([NSUserDefaults 
standardUserDefaults])));
     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([[NSObject alloc] 
init])));
     NSLog(@"%@", CFCopyTypeIDDescription(CFGetTypeID([[NSSet alloc] 
init])));
     NSLog(@"%@", 
CFCopyTypeIDDescription(CFGetTypeID([NSNotificationCenter 
defaultCenter])));

... spews ...

2003-01-09 22:17:26.077 asdfasdf[1835] CFArray
2003-01-09 22:17:26.079 asdfasdf[1835] CFDictionary
2003-01-09 22:17:26.079 asdfasdf[1835] CFArray
2003-01-09 22:17:26.142 asdfasdf[1835] CFType
2003-01-09 22:17:26.143 asdfasdf[1835] CFType
2003-01-09 22:17:26.143 asdfasdf[1835] CFType
2003-01-09 22:17:26.143 asdfasdf[1835] CFSet
2003-01-09 22:17:26.143 asdfasdf[1835] CFType

... and, as such, it appears that there is some potential to automate 
the test.

The 'conversion' method doesn't do any converting.  It simply does:

- (CFTypeRef) cfTypeRef
{
     if (.. test encapsulated object for CFness ..)
	    return encapsulatedObject;
     else
	    return nil;
}

I'm not going to pretend to speak for Ronald regarding adding a method 
to all Python encapsulated ObjC objects....

CF -> NS:

     Jack covered this in his message -- if all CF types inherit from a 
common base, then implementing a method that returns ref or nil, 
depending on if it is bridged.

b.bum