From: hongseok.yoon@...
Date: 2006-03-08T17:43:41+09:00
Subject: ridiculous behavoir of Array#push and Array#clear

See bellow code please.

      1 obj1    = "object1"
      2 obj2    = "object2"
      3 obj3    = "object3"
      4
      5 arr1    = Array.new
      6 arr2    = Array.new
      7
      8 arr1 << obj1
      9 arr1 << obj2
     10
     11 arr2 << obj3
     12
     13 puts "<arr1>"
     14 arr1.each {
     15     | element |
     16     puts element
     17 }
     18
     19 puts "<arr2>"
     20 arr2.each {
     21     | element |
     22     puts element
     23 }
     24
     25 arr1.push( arr2 )
     26 puts "<arr1 << arr2>"
     27 arr1.each {
     28     | element |
     29     puts element
     30 }
     31
     32 arr2.clear
     33 puts "<arr2.clear>"
     34
     35 puts "<arr2>"
     36 arr2.each {
     37     | element |
     38     puts element
     39 }
     40
     41 puts "<arr1>"
     42 arr1.each {
     43     | element |
     44     puts element
     45 }

result is...

<arr1>
object1
object2
<arr2>
object3
<arr1 << arr2>
object1
object2
object3
<arr2.clear>
<arr2>
<arr1>
object1
object2

In the last list of arr1, there's no object3. Why? Does Array#push()
method append the array as a refrence? If so, why it does? And after
arr2 had been cleared, I still can access to 3rd member of arr1 without
exceptions or errors.

Yes, I can use clone() method for Array#push. But before, I hope to
know the reason why RUBY's Array#push method works like above.

Thanks.