Re: Getting the index for an element in mutually referencing containers

[Mart van de Wege <mvdwege@gmail.com>]

Egil H H <ehh.public@gmail.com> writes:

> On Thursday, March 9, 2017 at 2:50:03 PM UTC+1, Mart van de Wege wrote:
>>
>>       Children : Offspring.Vector := Offspring.To_Vector(4);
>>
>>    Put(Integer(Father.Children.Find_Index(Child)));
>
>
> To_Vector adds empty elements to your list of Children, so Find_Index
> fails (probably dereferencing null or other erroneouse memory access)
> when trying to compare them to the Child. Removing the call to
> To_Vector seems to work as expected...

Aargh. So Find and Find_Index don't just skip empty elements, but die on
them? *That* was not clear from my reading of the spec.

And yes, in actual practice I expect to have sparse Vectors with a few
gaps not holding an Element. So how do I deal with this?

Mart

-- 
"We will need a longer wall when the revolution comes."
    --- AJS, quoting an uncertain source.