Module system_param 

Structs

FunctionSystem

Wraps a plain function into a System, holding its per-call SystemParam::State between runs.

SystemConfig

A system bundled with .after(...)/.before(...) ordering constraints, produced by IntoSystemConfig::after/IntoSystemConfig::before and consumed by Schedule::add_system.

Traits

IntoSystem

Implemented for any function whose parameters are all SystemParams — this is what lets a plain fn my_system(time: Read<Time>) be passed directly to add_system.

IntoSystemConfig

Lets .after(...)/.before(...) be called directly on a system — a plain function, closure, or anything else IntoSystem is implemented for — to declare where it must run relative to another system in the same Schedule:

System

A runnable system — the type-erased form IntoSystem produces, so different systems (different parameter lists) can live in the same Vec<Box<dyn System>>.

SystemParam

Anything that can be fetched as a system function parameter — implemented for Read/Write, Query, Local, Commands, tuples of SystemParams (so a function can take several), and a few others. You generally don’t implement this yourself unless you’re adding a new kind of parameter.