Factorio Forums

What?

The game should not auto-delete or auto-merge entries in the parameterization that have the Parameter checkbox checked, even if they are unused.
Essentially, please fix this bug.

Why?

Deleting or merging parameters is an inconsistency. If the player checks the parameter checkbox, it should be assumed that they want it to persist. Perhaps only using it as a variable. Right now, the game deletes parameters that are not used by entities in the blueprint. This happens even if they are used as a variable. Therefore it is possible to break the configuration of entities in a blueprint by deleting other entities.

Right now there is a very ugly workaround, which is to have a legendary (so bots don't build it) constant combinator somewhere in the blueprint holding the values.

Use cases of variable-only parameters:

• Have a parameter that is the input to a certain formula that computes what should go into combinators as constants. (I merely want to flip a sign...)
• Blueprint a decider combinator or any entity with logistic groups to emit/contain the ingredients of a recipe parameter, without the recipe parameter present anywhere.
• Have multiple numeric parameters with the same default value, which helps even if entities can only see one of them.

A user story

Say I want to set a value in a transport belt condition based on the number of Yumako tree plots I have. The value I want to set is different (by some carefully thought-out-constant factor) but I want to see "Number of Yumako Trees" as a parameter. This is a nice and simple use-case. The parameter is not used anywhere but as an input to a formula on a different parameter. But the game prevents me from having this. I either have to include a constant combinator in the blueprint or just note the formula in the blueprint description.

So I went and edited the Blueprint JSON. Not a very nice workaround. Later the game spuriously still ended up removing the "unused" parameter.