On Thu, 28 Jul 2016, Maciej Izak wrote:
2016-07-28 12:40 GMT+02:00 Michael Van Canneyt <mich...@freepascal.org>:
I don't see how you can solve nullable var parameters in native code.
I'd like to present how TNullable<T> works in my implementation (compilable
and runable program ;)
Yes, I remember you demonstrate it. But I think there are some caveats.
=== code begin ===
procedure Test1(var x: Integer);
begin
x := 1;
end;
Assume a is null before the call to test1:
test1(a);
1. What happens if this procedure is empty, i.e. no write is performed ?
(or it is performed conditionally)
On return, is a null or not ?
2. Assume your variable is null before the call to Test1.
What is the value on entry into Test1 ? i.e. what happens if
begin
if X=0 then
x:=1
else
X:=23;
end
3. How do you detect an actual write ?
4. What happens if Test1 is an external C procedure ?
Michael.
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