Modifier plugin request - proximity merge

Scripting forum isn’t really for requests afaik, thus I’m posting here. However I thought of a modifier that would be quite useful. (And other people may find it handy too, since it has a general use application.)

What I need is a way to dynamically weld vertices with a modifier. This would fix some problems where modifiers aren’t able to pass certain info down the modifier stack. Say I have an arrayed object following a curve, however the function to merge first and last in the array modifier has no way of interpreting the subsequent curve modifier in the stack. Likewise the curve modifier wasn’t designed to get that data passed down either. So with things like racetracks you always get this ugly seam when you do stuff like smoothing or solidify lower down in the modifier stack.

Yes, it could be solved by applying the modifiers and manually welding, however you then lose the flexibility that comes from using modifiers. Not to mention the resulting mesh geometry is no longer a proxy. To me, it seems much more convienient to maintain the dynamic behavior if possible.

So I’d like to be able to just simply weld vertices in an object based on proximity at some step in the modifier stack and get rid of the seams. If that’s too much overhead, perhaps it could be done by marking vertex groups on the mesh and only weld those to geometry that’s dynamically generated via previous modifiers. So instead of checking the whole mesh, only the check for vertices within a user defined distance near the marked ones. Doing it that way would still be good for dynamically merging loose ends togethether which is the main purpose for having this.

Anyone with coding skills up to this? Or does this exist somewhere, and I just don’t know what to search for?

https://developer.blender.org/T41748

Cool. Good to see others are talking about how useful it could be. Any idea how far off it is on the drawing board?