Context.groovy

class FromRole {
  static cap(String self) {
    self.toUpperCase()
  }
}

class ToRole {
  static uncap(String self) {
    self.toLowerCase()
  }
}

class Context {
  String from
  String to
  void setFrom(String value) {
    this.from = value
    this.from.metaClass.mixin FromRole
  }
  void setTo(String value) {
    this.to = value
    this.to.metaClass.mixin ToRole
  }
  def method() {
    println "from ${from.cap()} to ${to.uncap()}"
  }
}

def Context = { c ->
  return [c: c, context: new Context()]
}

def put = { map ->
 return [into: { x ->
    x.c.resolveStrategy = Closure.DELEGATE_FIRST
    map.each {k, v ->
      x.context["$k"] = v
    }
    x.c.delegate = x.context
    x.c.call()
 }]
}

// use Context
put from:"a", to:"B" into Context {
  method()
}