Recipe for Singleton class wit AutoHotkey

Singleton.ahk

;~ This is a singleton class - taken from: http://www.programering.com/a/MDN4YDMwATU.html
class Singleton
{
  ;~ Single cases registered property
  static _myInstance := 0
    
  ;~ Instantiation counts
  static _instanceCount := 0
    
  ;~ test property
  _myVar := 0
    
  __New() {
    MsgBox % "step2: <new> to create a new instance"
    if IsObject( this._myInstance ) {
      MsgBox % "Singleton class is already instantiated, use the <getInstance> method to obtain the existing singleton instance"
      return this._myInstance
    }
  }
    
  getInstance() {
    MsgBox % "step1: <getInstance> to get the singleton"
    if ( IsObject( this._myInstance ) = 0 ) {
      this._instanceCount++
      this._myInstance := new Singleton()
    }
    return this._myInstance
  }
    
  ; accessor to test property  
  myVar[] {
    get {
      this._myVar := this._myvar + 1
      return this._myvar
    }
  }
}

Singleton_Test.ahk

#Include %A_ScriptDir%
#Include Singleton.ahk

MsgBox % "**** The first run should use the New function."
testFunc()
MsgBox % "**** The second run should not use the New function."
testFunc()
MsgBox % "**** The third run should not use the New function."
testFunc()
ExitApp

testFunc()
{
  objA := Singleton.getInstance()
  MsgBox % "myVar: " ObjA.myVar "`ninstantiation times: "  objA._instanceCount
}