Set recipe does not work for two combinators providing input

[Aquillyne]

Items:
Decider combinator x 2
Buffer chest
Assembler

Connections:
Buffer --> Decider A input
Buffer --> Decider B input
Deciders A and B output --> Assembler (set recipe)

Decider logic:
A: Item A in buffer chest > Item B, output Item B = 1
B: Item B in buffer chest >= Item A, output Item A = 1

This should set the recipe of the Assembler which should effectively alternate between Items A and B. The actual result is that it sets the recipe one time (according to the logic, correctly), but then when the signals change the recipe is set to none.

If the Assembler is re-built at this point, the logic correctly resumes, flipping over to the other item. One item will be built, then the recipe is once again set to none.

[Aquillyne]

OK I've worked out this is an interaction with the logic that the recipe will not be set if there is any item in the trash slot.

This occurs because ingredients are loaded in during the previous recipe, and when the recipe completes, some ingredients are left over and these end up in the trash slot.

This makes it kinda difficult to change recipes as this is a very likely outcome when changing recipes.

[boskid]

Thanks for the report. That is not a bug. Reason why assembler circuit set recipe works that way is two-fold: first it solves issue of infinite trash storage where amount of trash would accumulate in the trash inventory every time a recipe is changed or cleared, and second is that it forces players to take a look and realize there are items to be taken out that need to be handled.

[IsaacOscar]

OK I've worked out this is an interaction with the logic that the recipe will not be set if there is any item in the trash slot.

This occurs because ingredients are loaded in during the previous recipe, and when the recipe completes, some ingredients are left over and these end up in the trash slot.

This makes it kinda difficult to change recipes as this is a very likely outcome when changing recipes.

It's not hard, just put an inserter to take stuff out.
The hard way is to ensure exactly the right number of ingredients are inserted, so time isn't wasted removing from the trash slots.