TL;DR
Game could provide API for items that are needed to craft something, but don't get used in process.What ?
I thought kovarex process and some modded recipes could benefit from that suggestion being implemented.Right now - 40 U-235 needs to be ingredient in Kovarex provess and it returns 41 U-235. If my suggestion was implemented, the recipe would require 40 U-235 and 2 U-238 as "capital/tool" that needs to be in machine and convert 3*U-238 into 1*U-235. You don't need to throw capital away and take back again each time recipe finishes.
... I already made image, but now I think it would work cooler if only 40 U-235 was "capital" U-238 could stay as it is (5 input->2 output)
Why ?
I think it's more logical, It simplifies player builds, it simplifies code (I guess.. I think right now kovarex process is only exception that needs to work differently with productivity modules than any other recipe)...I also don't think it would be hard to implement. Basically add array of items "capital" to recipe, if it is missing (=nil), then it would default to {} , then if there's not enough items in "capital" slot machine would be in disabled state.
I actually don't think I made compelling enough argument to convince anyone (if I read it, I wouldn't be convinced by my "why?" paragraph), but I really think it would be interesting idea, probably simplifying/opening new routes for modders. Realism-based mods could use assemblers as machine frame and then require items, like example inserters for assembling complex engines/circuits , require electro-magnet for splitting dusts recipe, etc. Right now - they would need to make separate machine for every recipe, which is .. kind of work intensive. I would for sure use this feature in my mods.