[fpc-devel] Parameters must match exactly?
fpc at mfriebe.de
Mon May 17 12:13:34 CEST 2010
On 17/05/2010 10:47, Mattias Gaertner wrote:
> On Mon, 17 May 2010 10:40:12 +0100
> Martin<fpc at mfriebe.de> wrote:
>> On 17/05/2010 10:29, Mattias Gaertner wrote:
>>> Theoretically: yes, this could work for classes.
>>> But as Jonas explained a few times: 'out' is *not* write only.
>>> Out is finalised and must therefore match exactly.
>>> And even write-only is not enough for "object"s because an ancestor
>>> has too less memory.
>> Hm, finalization isn't happening in the user code. So shouldn't be an
>> issue... and:
>> - are class-instance finalized? (maybe with interfaces)
>> - it's an implementation detail of the compiler => it could (maybe does)
>> happen, in the calling code (where type info is known)
>> memory is allocated on the heap
>> s and x are both just pointers => so the size matches
>> Actually x is a pointer to s, and s a pointer to the memory. but s can
>> be changed, so the memory can be re-allocted.
> No, for example:
I quite clearly wrote "class-instance"
I am aware it doesn't work for object.
> TAncestor = object
> i: string;
> TMyObject = object(TAncestor)
> j: string; // need more mem
> procedure Doh(out o: TMyObject);
> o.j:='3'; // writing beyond
> procedure A;
> o: TAncestor; // limited mem
> fpc-devel maillist - fpc-devel at lists.freepascal.org
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