Re: [Pyobjc-dev] memory management.

[Ronald O. <ous...@ci...>]

Jonathan,

I agree that we should try to abstract away manual management of 
reference counts. Until a few days ago I believed we already reached 
this point.

There are now two sets of ...

1. Bill mentioned that it is common in some Objective-C code to transfer
    ownership of returned objects to the caller (He's the resident expert
    on these issues, I'm learning Objective-C/Cocoa as a go along).

    It will be hard to correctly identify all these cases. IMHO this 
shouldn't
    keep us from doing away with autorelease/release/retain in Python 
code:
    it will just be a little harder to correctly wrap an Objective-C 
class
    library. As wrapping an Objective-C class is an order of magnitude 
simpler
    than wrapper other 'native' code that should not be a problem.

2. Bill also mentioned a coding style that uses 'autorelease' to make 
sure
    that an object is around to the end of the current loop through the
    eventloop (which in case of non-GUI programs may be quite a long 
time).

    I don't really like this coding style, so IMHO it is not a problem 
to use
    'obj.retain().autorelease()' in these cases, instead of just
    'obj.autorelease()'. I'm also pretty sure that doesn't really have 
anything
    to do with the automatic management of refcounts by the bridge.

3. The NSMutableArray class cluster (and probably all NS<DataStructure> 
class
    clusters) play games with reference counts during allocation. This 
is not
    a problem if you use the common Objective-C idiom, but it is when 
you try
    to automate management of reference counts.

    Basicly the issue is that the Objective-C manual strongly suggest 
that the
    following two lines should be equivalent, but they are not for these 
class
    clusters:

    NSArray.alloc().autorelease().init()	# Basicly what the bridge does
    NSArray.alloc().init().autorelease()   # Common Objective-C idiom

    I'm thinking on how to fix this. The one requireing the least amount 
of
    engeneering is saying "Don't use 'alloc().init()' for these class 
clusters",
    or even "Don't allocate Objective-C containers from Python". I don't 
really
    like this and am thinking on how to fix this in a correct manner.

Ronald