Wanting to adjust turret targeting priorities

[Illiander42]

I'm wanting to write a simple mod to let you say "this turret shoots the thing farthest away, this one shoots the thing nearest" and looking through the documentation I can't see how to do it.

Is there a mod that already does this, or is it something we can't do?

Why:

I want to set up a combined defence line where the laser turrets prioritise the stuff that stays at range (currently just spitters), and the bullet turrets take the stuff against the wall.

[321freddy]

AFAIK turrets don't have a prioritising mechanic built in, so you would have to simulate it.
You can set the shootng target of a turret using LuaEntity::shooting_target
Although I don't know how this could be used in a way that doesn't completely kill your performance.
Maybe use the events on_entity_damaged and on_entity_died with the cause parameter to script the desired behaviour.