Protecting object attributes in Rebol

Question

I'm trying something quite basic in Rebol. I want to have a simple instance hierarchy - a question base instance and some question sub-instances. And I want to have some instance attributes protected.

What I'm doing now is:

_question: make object! [
    id: none
    type: none
    text: none ]

    question-text: make _question [
        type: 'text

    new: func [
        id' [integer!]
        text' [string!]
    ] [
        make self [
            id: id'
            text: text'

            protect [ id type text ]
        ]
    ]
]

But then this fails:

qt1: question-text/new 1 "q-text1"
qt2: question-text/new 2 "q-text2"

Once I make the second instance qt2, I get:

Script Error: Word id is protected, cannot modify

Next idea is then to move the protected fields out of _question and put them into question_text - even if I wouldn't like that. But that just leads to the same error.

Note: I'm currently doing this with Rebol2, but would ideally also get my things running in Rebol3 and in Red. And I would like to avoid hacks (sure - that's vague, things like Python getitem()/setitem() tricks would be fine). Then I'd prefer to have the fields unprotected.

Answer 1

There are some binding considerations here. This works, but is subject to the quirky nature of Rebol 2's 'protect function and contexts:

new: func [
    id' [integer!]
    text' [string!]
    /local object
][
    object: make self []
    object/id: id'
    object/text: text'
    protect bind [ id type text ] 'object
    object
]