From: Hannes Wyss <hannes.wyss@...>
Date: 2006-03-08T18:22:38+09:00
Subject: Re: ridiculous behavoir of Array#push and Array#clear

inspect will give you the answer:

On 3/8/06, hongseok.yoon@gmail.com <hongseok.yoon@gmail.com> wrote:
>       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 puts arr1.inspect
->     [ "object1", "object2" ]

>      19 puts "<arr2>"
        20 puts arr2.inspect
->     [ "object3" ]

>      25 arr1.push( arr2 )
>      26 puts "<arr1 << arr2>"
        27 puts arr1.inspect
->     [ "object1", "object2", [ "object3* ] ]
        # notice that the third Element of arr1 is not obj3, but arr2!

>      32 arr2.clear
        # fine, emptying arr2...
>      33 puts "<arr2.clear>"
>      34
>      35 puts "<arr2>"
        36 puts arr2.inspect
->     [ ]

>      41 puts "<arr1>"
        42 puts arr1.inspect
->     [ "object1", "object2", [  ] ]
        # the third Element of arr1 is still arr2, it just has been cleared,
        # so not a trace of obj3...

> 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.
...or you could do:
       25 arr1.concat( arr2 )
->    [ "object1", "object2", "object3" ]

for any questions like that: try irb - I can only recommend it..

hth

Hannes