Pointer ofNull method naming

[Maurizio Cimadamore]

On 13/11/2019 22:15, Ty Young wrote:
>
> On 11/13/19 3:19 PM, Maurizio Cimadamore wrote:
>>
>> On 13/11/2019 12:43, Ty Young wrote:
>>>
>>> On 11/13/19 2:28 AM, Maurizio Cimadamore wrote:
>>>> I'm ok with making the documentation more precise (I'm not sure I 
>>>> like ofTyped()). Can you please clarify a bit what you mean by 
>>>> 'filler' ? Like passing null ptr to a struct setter?
>>>
>>>
>>> Not struct types but more primitive native types like Pointer<Byte> 
>>> or Pointer<Integer>.
>>>
>>>
>>> As an example, you have a function like this:
>>>
>>>
>>> int foo(Pointer<Pointer<Byte>> array, Pointer<Integer> size);
>>>
>>>
>>> But what you're actually interested in is at index 0 of the array, 
>>> so "size" isn't needed and allocating a new Pointer would be a waste.
>>
>> Not sure I follow - if you are interested in index 0, doesn't that 
>> mean that the array would need to have at least _one_ element (e.g. 
>> size >= 1) ?
>
>
> It does. It's just that the data that is actually desired is located 
> at index 0, so doing:
>
>
> array.get().get()
>
>
> returns index 0 anyway.
>
>
> For context, the function in question returns a Pointer to an array in 
> the format:
>
>
> Index 0 = number of items
>
> index 4 * number of item = bitmask of a given item

Really confused by this example - if the size is always at position 0 of 
the array, then what is the second argument Pointer<Integer> used for?

I'm trying to understand whether this is really a 'new' use for 
Pointer.ofNull, or whether you are just exploiting the fact that the 
underlying function you are using happens to work even if the second 
parameter is null. in other words, I'm having problems understand what 
you mean by this 'filler' capability of Pointer.ofNull.

Maurizio

>
>
> However, one might only be interested in index 0 or in this case, the 
> number of items, so allocating another Pointer just to make the 
> function call seems like a waste.
>
>
> It seems like *some* functions check whether a given Pointer is null 
> or not but not all do such as the functions I'm working with. It just 
> fills the array Pointer regardless.
>
>
>>
>> Maurizio
>>
>>
>>>
>>>
>>>>
>>>> (p.s. in these cases we have been also discussing bringing back 
>>>> special treatment for Java null, so that null is re-interpreted to 
>>>> Pointer.ofNull)
>>>
>>>
>>> I haven't gone too deep down the rabbit hole, but I see 
>>> "LayoutTypeImpl.nullType" in BoundedPointer. Isn't that the null 
>>> interpretation for a Pointer?
>>>
>>>
>>>
>>>>
>>>> Maurizio
>>>>