Re: how to delete from Ada.Containers.Doubly_Linked_Lists

["Björn Lundin" <b.f.lundin@gmail.com>]

On 2014-08-18 21:57, Jeffrey Carter wrote:
> On 08/18/2014 11:51 AM, Björn Lundin wrote:

>> How should a nice solution look like ?
> 
> You probably ought to read about "tampering with cursors" in the ARM (A.18.3).
> In your case, iterating over the list needs the list to remain unchanged until
> iteration finishes. Deleting during iteration would violate this.

Hmm, yes I see that now.

> This restriction is intended for safety, and sometimes seems onerous.

That was my suspicion

> I've had
> to iterate over one data structure, storing cursors in another data structure,
> then iterate over the 2nd data structure to delete using the stored cursors.

Yes, basically what my last sample did - saving the cursor 'c' into
'C_Save' and delete outside the loop. That is what I thought was
inelegant/clumpsy

> You can delete during iteration if you don't invoke an Iterate subprogram:

Still a bit inelegant, but thanks for the example.
It is way better that mine.


/Björn