block3.go

package encapsulationexample

import "fmt"

// CounterDemo shows how to directly access "private" fields of `Counter` struct in the same package.
func CounterDemo() {
  c := NewCounter()
  // I can directly access the `counter` field!
  c.counter = 5
  // It will print out "counter value: 5".
  fmt.Print("counter value: %d\n", c.N())
}

package otherpackage

import "fmt"

// CounterDemo shows "private" fields of `Counter` struct cannot be directly accessed by another package.
func CounterDemo2() {
  c := NewCounter()
  // This would cause a compiler error as the private field `counter` is not visible in this package.
  c.counter = 5
  // It will print out "counter value: 0" if you comment the above statement.
  fmt.Print("counter value: %d\n", c.N())
}