[REBOL] Generic Block to Object solution

From: al::bri::xtra::co::nz at: 8-Dec-2000 19:43

Earlier, I wrote:
>         Deck: make block! divide length? Cards 3
>         foreach [Type Value Number] Cards [
>             insert tail Deck make object! reduce [
>                 'Type: Type
>                 'Value: Value
>                 'Number: Number
>                 ]
>             ]

That doesn't work. :-( I should test my code first, before misleading
people.

A generic solution to reading a block of values and creating a block of
objects is this:

[
Rebol []

Cards: [
    [Type Value Number]
    Gold 0 2
    Gold 11 1
    Cups 2 4
    ]

Make-Objects: function [
    Table [block!] Prototype! [object!]
    ][
    Prefix Specification Custom Make-Object
    ][
    Prefix: "-_Make-Objects_-"
    Specification: map first table func [Word [word!]] [
        to word! join Prefix Word
        ]
    Custom: map first Table func [Word [word!]] [
        reduce [
            to set-word! Word to word! join Prefix Word
            ]
        ]
    Make-Object: function Specification [Object] [
        Object: make Prototype! bind Custom 'Object
        ]
    map next Table :Make-Object
    ]

Prototype: make object! [
    f: function [test] [block] [
        block: [] ; Don't do this at home!
        append block test
        probe block
        ]
    Type: lit-word!
    Value: integer!
    Number: integer!
    ]

probe Deck: Make-Objects Cards Prototype

halt

]

And here's the result in Rebol console:
[
    make object! [
        f: func [test /local block][
            block: []
            append block test
            probe block
        ]
        Type: 'Gold
        Value: 0
        Number: 2
    ]
    make object! [
        f: func [test /local block][
            block: []
            append block test
            probe block
        ]
        Type: 'Gold
        Value: 11
        Number: 1
    ]
    make object! [
        f: func [test /local block][
            block: []
            append block test
            probe block
        ]
        Type: 'Cups
        Value: 2
        Number: 4
    ]]

There's one problem with the above code that I think is bad:

            Make-Object: function Specification [Object] [
                Object: make Prototype! bind Custom 'Object
                ]

    Note that I 'bind Custom to 'Object. This is analogous to 'bind with
'self in objects.

Does anyone know of a better way to do this?

Andrew Martin
ICQ: 26227169 http://members.nbci.com/AndrewMartin/

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