On 27.09.2013 08:03, Xiangrong Fang wrote:
Hi Sven,
2013/9/26 Sven Barth <pascaldra...@googlemail.com
<mailto:pascaldra...@googlemail.com>>
As you can see you are constructing a TTreeInteger class inside
TTreeInteger.Clone and nothing in the world afterwards can turn it
into a TTreeInt.
Do you mean that casting TTreeInteger into TTreeInt is not possible
because this is to cast a parent class into a child class? If so, how
this is possible (mentioned in my earlier question about avoid typecasting):
type
TIntTree = class(specialize TTree<Integer>)
end;
var
it1, it2: TIntTree;
begin
... ...
it2 := TIntTree(it1.FirstChild);
end.
This is also casting TTree$Integer (parent class) to TIntTree (child class)?
Depends on how you add the nodes. If you use TIntTree.Create(...,
SomeOtherIntTree) then the class instance which is added to the FItems
of the parent is a TIntTree. If you use TTree$Integer.Create then itwill
be a TTree$Integer. Also see my other mail I just sent regarding your
Clone call.
I'd suggest you to compile your code (for testing) with -CR which will
turn all object type casts to "as" typecasts thus they will raise
exceptions if the typecast is not possible (e.g. if you are casting a
TTree$Integer instance to a TIntTree). This way you can find out where
you still have problems.
Regards,
Sven
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