Re: Help with NSPointerArray and NSMapTable

On Sep 23, 2009, at 0:20, Nat! wrote:

>
> Am 21.09.2009 um 21:14 schrieb Christiaan Hofman:
>
>>
>> On Sep 21, 2009, at 20:54, Nat! wrote:
>>
>>> I would try NSPointerFunctionsOpaqueMemory (shouldn't retain/ 
>>> release or do weird GC stuff on the value),
>>> + NSPointerFunctionsIntegerPersonality (use value as hash and  
>>> equality) and pass in the integer casted in as void *.
>>>
>>> If that's right, then I guess the documentation is sufficient ;)
>>>
>>> Ciao
>>> Nat!
>>
>> Thanks. The problem I have with the docs is that it is not obvious  
>> to me what the "value" is. Is this the pointer itself, or the  
>> target of the pointer? If it's the pointer, they should call it the  
>> pointer, otherwise they should explain which value they're talking  
>> about. For instance, if you are right, than for  
>> NSPointerFunctionsIntegerFunctionality the value is the pointer  
>> itself (which actually isn't a pointer), while for  
>> NSPointerFunctionsStructPersonality, the struct is the target of  
>> the pointer. Quite frankly, that distinction is not clear for me by  
>> reading the docs.
>>
>
> If you look at NSMapTable pre 10.5, there used to be a distinction  
> between NSMapTableKeyCallBacks and NSMapTableValueCallBacks, then it  
> would have been a little bit clearer what value meant. I'd wager a  
> bet that NSPointerFunctionsOptions are just a shortcut to setup the  
> callback functions of the NSPointerFunctions that are then really  
> used internally, but because of the various memory options it  
> probably got tedious to enumerate the various structs.
>
> Anyway with regard to NSPointerFunctionsOptions value only means the  
> void *. If you want to use structs as values, you'd need to use  
> NSPointerFunctions directly and specify at least the size of your  
> struct with the sizeFunction property. And then I'd try  
> NSPointerFunctionsMallocMemory + NSPointerFunctionsStructPersonality  
> (for a blob of data, like NSRect) with that. (And I am only using  
> NSPointerFunctionsMallocMemory because it sounds familiar)
>

And shouldn't I also use NSPointerFunctionsCopyIn? It is not really  
clear to me what's the relation between that option and  
NSPointerFunctionsMallocMemory.

Christiaan

> Caveat:this is just from reading the dox and having used NSMapTable  
> and friends excessively before.
>
>> Apart from this, the 64-bit docs warn against type-casting an  
>> NSInteger as a pointer, but that seems to be exactly what  
>> NSPointerArray expects me to do? If they go against their own docs  
>> I really think they should be more clear.
>>
>
> I have no opinion on that, I haven't migrated to 64 bit yet :)
>
> Just perusing the documentation, I love it how easy things have  
> become with GC. Now we have weak barriers and strong barriers to  
> consider instead of retain/release and so much more convenient API  
> to use. We're getting really close to Java now. Exciting times.
>
> Ciao
>   Nat!
> ------------------------------------------------------
> Thanks for paying my rent. -- EVH