[Lazarus] VirtualTreeView, Absoluteindex example on freepascal.org

[Frederic Da Vitoria]

2013/9/12 Jürgen Hestermann <juergen.hestermann at gmx.de>

>  Am 2013-09-12 14:50, schrieb Frederic Da Vitoria:
>
>
>  Can someone explain what the line
>>   if VST.AbsoluteIndex(XNode) > -1 then
>> actually means?
>>
>
>  I didn't look at the code, but usually index = -1 means that the item
> was not found. So maybe AbsoluteIndex's result should actually be signed?
>
>
> And how would it ever reach the value -1?
> Obviously there is no code that sets it to this value,
> otherwise it would not compile with Cardinal type.
>

Once again, I did not look at the code. My remarks only come from my
memories of how VirtualTreeView worked with Delphi 6. The code has
obviously much changed since. I was only attempting to answer to your
question: this is probably the reason. Is it still working? Obviously not.
What should be done? I see 2 options: either restore the old functionality
if needed or (if indeed this test never had any real use) remove this test
from the example. How does code handle when AbsoluteIndex does not find an
item? I just took a look at v5.2.0. If I read the code correctly, if the
parameter is the root, AbsoluteIndex will answer 0. If the parameter is not
found, AbsoluteIndex will answer 0 too. Is this deliberate?



>  In this example, I guess the test is to avoid a bug if AddChild does not
> manage to insert the root node. I don't know if AddChild could create a
> node without inserting, but this is what the code seems to be testing.
>
>   But it is a useless "if" statement that doesn't test anything.
>

Now yes. Once upon a time maybe not.

-- 
Frederic Da Vitoria
(davitof)

Membre de l'April - « promouvoir et défendre le logiciel libre » -
http://www.april.org
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