Status Quo
2.0 added the ability to filter items to all vanilla inserters and removed dedicated filter inserters in the process. This was a very welcome change to reduce the number of items. The ability to do so is available from the start, unable to be turned off by mods. Mods can of course remove filters from individual prototypes, but can't retroactively add them, e.g. when a technology is researched.Proposal
I propose adding a Modifier type InserterAllowFilterModifier extending BoolModifier that - once unlocked - enables the use of filters on inserters. Similar to RailSupportOnDeepOilOceanModifier (and others), this would modify a boolean on a force. To preserve the current vanilla experience, this boolean would start out as true, with mods having the ability to override this on force creation.Why?
Unlocking filtering for inserters via research would be a meaningful progression unlock for the early game, which could be useful for mods overhauling the early game. If integrated in vanilla, this would reduce interface complexity in the start for newcomers, aligning well with the intent of the use of trigger technologies for electronic circuits and steam power. It would also provide a good trigger for unlocking a tips and tricks entry for filters on inserters.A similar argument can be made for filters on splitters, or even the input and output priorities on them.
