Question

present code is currently structured as follows:

System.Timers.Timer myTimer;

public void FirstMethod() {
  myTimer;= new System.Timers.Timer();
  myTimer.start();
  SecondMethod();
}

public void SecondMethod(){
  //several things happen here and then
  myTimer.stop();  
}

I’ve been advised that I could use using to correctly garbage collect the Timer object. So I’ve tried to apply something like the following to my code (taken from here):

using (SomeClass someClass = new SomeClass())
{  
someClass.DoSomething();  
}  

I assume the following will error because myTimer is not known by SecondMethod()?

public void FirstMethod() {
  using (System.Timers.Timer myTimer = new System.Timers.Timer())   
  { 
  myTimer.start();
  SecondMethod();
  }
}

public void SecondMethod(){
//several things happen here and then
myTimer.stop();  
}

Answer 1

You wrap an object that implements the IDisposable interface in a using block when it makes sense to do so. In this case it does not because the object must be valid at a higher scope. Remember, a using statement is just shorthand (syntactic sugar) for this:

var myDisposableObj = new Whatever();
try
{
    // use myDisposableObj.  If an exception is thrown
    // in here somewhere the call to Dispose() still occurs.
}
finally
{
    myDisposableObj.Dispose();
}

In your case you need to ensure that you call Dispose() on the object when you are done with it (and in a manner that accounts for exceptions which may be thrown that would prevent the call to Dispose() from taking place). You need the Timer to stick around for a while, so a using block is out of the question.