Re: Help with NSPointerArray and NSMapTable

On 23 Sep 2009, at 10:58, Christiaan Hofman wrote:

>
> On Sep 23, 2009, at 10:42, Jonathan Dann wrote:
>
>> On 23 Sep 2009, at 01:27, Christiaan Hofman wrote:
>>
>>>
>>> On Sep 23, 2009, at 1:25, Jonathan Dann wrote:
>>>
>>>>
>>>> On 23 Sep 2009, at 01:10, Christiaan Hofman wrote:
>>>>
>>>> [snip]
>>>>
>>>>> Right, that's basically what I proposed as well. So I also need  
>>>>> to use this for simple types like CGFloat that are not pointer- 
>>>>> sized?
>>>>
>>>> Yep.
>>>>
>>>> [snip]
>>>>
>>>>> Nice samples, that surely helps. Thanks. I just find it  
>>>>> confusing that for NSInteger it works differently. Though I  
>>>>> guess I could do the same.
>>>>
>>>> No problem. When you're doing this, you're not casting an integer  
>>>> to a pointer, so AFAICT the caveats in the 64-bit docs don't  
>>>> apply here.
>>>>
>>>> Jonathan
>>>
>>> As I understand it now, you do cast an integer to a pointer when  
>>> you use NSPointerFunctionsIntegerPersonality. So these caveats do  
>>> apply.
>>
>> Yeah but you don't have to use the integer personality with  
>> integers or floats. If you have a struct with a single int then you  
>> can case between the struct and an int without loss of precision.
>> I'm pretty sure that's what we're doing here. See:
>>
>
> But would you have to use the intermediate struct? Can't I just use  
> e.g. a CGFloat (passed in by address) directly using  
> NSPointerFunctionsStructPersonality? As I understand it this option  
> does not really care about the exact data type, only a blob of  
> memory of a certain size.

Yeah, that's what I was getting at. You don't need the intermediate  
struct, just the struct personality.

> But I was (also)  talking about directly adding NSInteger with  
> NSPointerFunctionsIntegerPersonality.

Sorry, I get you now. My bad.

> Christiaan
>
>> http://www.algorithm.com.au/downloads/talks/objective-c-internals/objective-c-internals.pdf
>>
>>> Christiaan
>>>
>>
>