const classafIoc::ConcurrentState

A helper class used to store, access and retrieve mutable state within a const class. For IoC this means your services can be declared as perApplication or singleton scope.

ConcurrentState wraps a state object in an Actor, and provides access to it via the withState and getState methods. Note that by their nature, these methods are immutable boundaries. Meaning that while all data in the State object can be mutable, but data passed in and out of the methods can not be.

A full example of a mutable const map class is as follows:

const class ConstMap {
  const ConcurrentState  conState  := ConcurrentState(ConstMapState#)
  
  Str get(Str key) {
    getState {
      it.map[key]
    }
  }

  Void put(Str key, Str value) {
    withState {
      it.map[key] = value
    }
  }
  
  ** helper method used to narrow the state type
  private Void withState(|ConstMapState| state) {
    conState.withState(state)
  }

  ** helper method used to narrow the state type
  private Obj? getState(|ConstMapState -> Obj| state) {
    conState.getState(state)
  }
}

class ConstMapState {
  Str:Str  map := [:]
}