Hi Juraj,

On Mon, Sep 14, 2015 at 4:56 PM, Juraj Kubelka <juraj.kubelka@gmail.com> wrote:

Hi,

I have a test case like that:��
-=-=-
testIncrementBy
prefix := MyObject new numbers: #(1 10); yourself.
prefix incrementBy: 10.
self assert: prefix numbers equals: #(1 20).
-=-=-

and the byte code starts like that:
-=-=-
57 <40> pushLit: MyObject
58 <CC> send: new
59 <88> dup
60 <21> pushConstant: #(1 10)
-=-=-

If I run the test case, it is green, but the byte code changes into:
-=-=-
57 <40> pushLit: MyObject
58 <CC> send: new
59 <88> dup
60 <21> pushConstant: #(1 20)
-=-=-

The #incrementBy: method looks like:
-=-=-
incrementBy: aNumber
numbers at: 2 put: (numbers at: 2) + aNumber
-=-=-

Is it correct that it also changes the method byte code?��

No, ut this does happen. ��hat I suspect you're seeing is the fact that in the Pharo and Squeak implementations, literals are not immutable.�� So if you were to assign to a literal Array in a method's literals that assignment would not cause an error, and worse, would not be visible because the mehtods source code would be unchanged.

We shall have a proper fix for this in a future release where we will support fully immutable literals.�� For now the correct respponse shoudl be to find out where in your code the literal is assigned to and to not do that.�� Of course adding a copy is also fine.

��

I can put "#(1 10) copy�� into the test case.��
I am just curious if it is a feature or bug.��

It's a bug, but an ancient one.�� Some Smalltalks, such as VisualAge and VisualWorks have fixed this by introducing support for immutable objects, but the {haro/Squeak Vms have yet to provide this.�� I expect to implement it in Spur some time next year.

��

Tested in Pharo4.0, Latest update: #40613.

Cheers,
Juraj

_,,,^..^,,,_

best,��Eliot