Any sample to declare local varible? about activej HOT 2 OPEN

Hi, @inshua

You can create an expression for a new local variable using the Expression#let method.

To create a for cycle you can omit creating a local variable i manually and use the Expression#iterate method that generates a for cycle for you.

Let’s say you have an interface Counter:

public interface Counter {
  int countSum();
}

and you want to generate a class that implements countSum() like this:

public int countSum() {
  int sum = 0;
  for (int i = 0; i < 100; i++) {
     sum += i;
  }
  return sum;
}

You can do this with the following expression:

Counter counter = ClassBuilder.create(Counter.class)
     .withMethod("countSum",
           let(value(0), sum ->
                 sequence(
                       iterate(
                             value(0),
                             value(100),
                             i -> set(sum, add(sum, i))),
                       sum
                 )))
     .defineClassAndCreateInstance(DefiningClassLoader.create());

First, you create a local variable sum and set it to 0. That is let(value(0), sum -> …). Then you iterate from 0 to 100 and set sum to be equal to a sum of i and sum.

You need to use the sequence() expression and pass sum as the last argument in order to instruct the method that it needs to return the sum in the end.

The above example refers to the master-5.5 branch. let(), value(), sequence(), iterate(), set(), add() methods are imported from the Expressions class.

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@eduard-vasinskyi thank you for response.

Got it, I understand why it's so designed now, this will make a life scope for a variable, like sum in above. Thank you.

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