On Fri, Jul 27, 2018 at 11:15 AM, Ryan Joseph <r...@thealchemistguild.com>
wrote:
> I never use Free directly so I had no idea. How is that even accomplished
> in the language? I thought it was just a method and behaved accordingly.
>
> If it is magic then how do we call other methods on nil objects? There are
> times that would be handy if I could control it.
It's not a magic, it's explicit check for the value of "Self" within a
method.
Self would point to an actual instance of an object, if it's nil. Free
method won't do anything.
type
TRobust = class(TObject)
public
v : Integer;
procedure RobustMethod;
end;
procedure TRobust.RobustMethod;
begin
if Self = nil then Exit; // remove or comment out this line to start
getting AVs
v := 5;
end;
var
r : TRobust;
begin
r := nil;
r.RobustMethod;
end.
You could consider this a sanity check, similar to checking any other input
parameters.
thanks,
Dmitry
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