[geos-devel] Request for Eyeballs

[Sandro Santilli]

On Fri, Jul 24, 2020 at 12:07:44PM +0200, Sandro Santilli wrote:
> 
> The ownership of those SegmentStrings is not documented in
> NodedSegmentString.h, which would help. My impression is that
> those segment strings should be shared pointers, to overcome this
> long standing issue (it was a problem before snaprounding as well).

More information. I think the primary problem with this API is that
the ownership of SegmentString in Noder.h is not properly documented.

Comments are even clearly expressing the confusion:

     * Some Noders may add all these nodes to the input SegmentStrings;
     * others may only add some or none at all.

The methods defined for a Noder are:

  virtual void computeNodes(std::vector<SegmentString*>* segStrings) = 0;
  virtual std::vector<SegmentString*>* getNodedSubstrings() const = 0;

What isn't clear is:

  - Who owns the SegmentString passed to computeNodes ?
  - Who owns the SegmentString returned by getNodedSubstrings ?
  - Can the same SegmentString be present in both input and output
    containers ?

I think these questions should be answered with proper documentation
in that class, and then we need to make sure all subclass implement
the documented semantic properly.

Using shared pointers of those SegmentStrings may help simplifying
the implementations, with the downside of some more overhead. But
other implementations could be made to work, as long as it is clear
who is responsible for what...

--strk;