How are closures implemented in scala?

Question

How are the variables outside of the scope of the function pulled into the function when it\'s created? I tried decompiling, but I had trouble understanding it. It looked

Answer 1

Here is the Bytecode for the following method containing a closure:

def run()
{
val buff = new ArrayBuffer[Int]();

val i = 7;

buff.foreach( a =>  {  a + i  }  )
}

Bytecode:

  public class com.anarsoft.plugin.scala.views.ClosureTest$$anonfun$run$1 extends   scala.runtime.AbstractFunction1$mcII$sp implements scala.Serializable {

// Field descriptor #14 J
public static final long serialVersionUID = 0L;

// Field descriptor #18 I
private final int i$1;

public ClosureTest$$anonfun$run$1(com.anarsoft.plugin.scala.views.ClosureTest $outer, int i$1);

...

The Compiler generates a new ClosureTest$$anonfun$run$1 with a constructor with two fields for the variables outside the scope, e.g. i and this of the calling class.