Re: Map iteration and modification

["G.B." <bauhaus@notmyhomepage.invalid>]

On 01.01.24 21:55, Dmitry A. Kazakov wrote:

>> Would it not be possible to get these benefits using a different
>> approach? I think the use case is clearly stated:
>>
>> First, find Cursors in map =: C*.
>> Right after that, Delete from map all nodes referred to by C*.
> 
> Right. Find cursors, store cursors in another container, iterate that container deleting elements of the first. Now, consider that the cursors in the second container become invalid (dangling pointers). If you wanted to delete them immediately from the second container, you would return the square one! (:-))

OK, yet if indicating nodes in a container is designed to survive
any deletions, leaving nothing dangling i.e., doesn't this limit
the way in which implementations can store nodes?
Seems like every "pointer" (= (Container, Position)) needs to know
its element, and/or the container will have to equip its storage
management with a "vacuuming" algorithm accordingly.

Transactions seem more flexible (a locking flag in a sequential
algorithm?), a dedicated operation looks simpler than both.