I'm using TObjectList.Sort successfully but, I suspect, not particularly
elegantly. In fact, I have a suspicion I'm doing something dumb..
It seems that my callback function has to be in the implementation
section (with no declaration) or the compiler complains. This had me
scratching my head for a while because within that function I need to
access objects, functions and procedures of the form which owns the list
I'm trying to sort. I have got round this by giving the object in my
list a Parent property of type of the form.
This might be easier to explain with some code fragments:
type
TMyForm = class;//forward declaration
TMyObject = class
private
public
/ /ID : integer;
Parent : TMyForm;
end;
TMyForm = class(TForm)
bla
HolyGrail : TMystery;
private
bla
bla
public
MyObjectList : TObjectList;
bla
end;
implementation
function MyFancySort(item1, item2 : Pointer) : integer
var
/ /obj1, obj2 : TMyObject;
begin
//now provided I have set the parent property to Self when creating the
TMyObjects and adding them to the list, I can access stuff on the form thus:
obj1 := TMyObject(item1);
obj2 := TMyObject(item2);
if obj1.Parent.HolyGrail.SomeFunction(obj1.ID) >
obj2.Parent.HolyGrail.SomeFunction(obj2.ID) then
bla bla you get the picture
end;
It works but it aint pretty - surely there's an easier way of getting at
stuff on the form? If I try to declare the callback function anywhere
where it would 'naturally' get at stuff on the form the compiler
complains that a 'variable required'.
Apart from the question of technique above, when I run this it is
surprisingly slow. Is there any way of knowing the progress of a Sort ?
Thanks for any suggestions...
Dave
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