[fpc-pascal] Question about System.Move()

[Sven Barth]

Am 09.01.2021 um 22:54 schrieb Bart via fpc-pascal:
> On Sat, Jan 9, 2021 at 8:14 PM Yuriy Sydorov via fpc-pascal
> <fpc-pascal at lists.freepascal.org> wrote:
>
>>> So, I'll use a for loop to copy the data.
>>>
>>> I assume that doing Arr[Index] := Default(T) will also finalize the
>>> element if that element ismanaged?
>> For class object instances call Arr[Index].Free, for other managed types or records containing managed types
>> Finalize(Arr[Index]) should work.
> In the base class, is there a way to check wether Arr[Index] is an
> object instance or a managed type or a datatype containing a managed
> type?

If by "base class" you mean the generic class (and not a base class in 
the object hierarchy sense), then you can use the IsManagedType 
intrinsic which is available since 3.2.0.

> Now the for loop (I abandoned the use of Move) does something like this:
>    Arr[NewIndex] := Arr[OldIndex];  //do I have to finalize/free
> Arr[NewIndex] also in this case?
No, the compiler will handle that correctly (it's just a normal 
assignment after all).

>    Arr[OldIndex] := Default(T);  //I understand this is not enough in those cases
This is only not enough for class instances if they should be Free'd. 
For everything else this is indeed enough.

Regards,
Sven