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[REBOL] Re: Does the REBOL book clarify REBOL semantics?

From: lmecir:mbox:vol:cz at: 22-Nov-2000 22:02

> At 16:05 21/11/00 +1300, Andrew Martin kindly replied: > > [snip] > > >Either the argument is a series! or a object! then it's passed as a
> >otherwise it's passed as a copy. Check out pages 87 through 90 of the
> >manual PDF for more. > > So series' and objects are passed by ref while all else are > passed by copy? >
My point of view differs a lot here. Statement #1: * In Rebol all arguments are passed by value, regardless of their type. * proof: function [argument] [check] [ check: func [arg] [ print ["Arg:" mold arg] arg: either arg = true [false] [true] print ["Changed arg:" mold arg] ] print ["Argument supplied:" mold argument] check argument print ["Argument after return:" mold argument] ]
>> proof true
Argument supplied: true Arg: true Changed arg: false Argument after return: true
>> proof false
Argument supplied: false Arg: false Changed arg: true Argument after return: false
>> proof [1 2]
Argument supplied: [1 2] Arg: [1 2] Changed arg: true Argument after return: [1 2] The above means, that the Rebol argument passing mechanism is uninteresting from this point of view. The next natural question may be: Are the benefits of "By Reference Argument Passing" lost for the Rebol users? The answer sounds: "No", and here is why: Statement #2: * Some Rebol values can reference other Rebol values. * Examples: a) A Rebol word can reference the value the word "contains". b) A Rebol series can reference the values the series "contains", moreover, it can even reference all the values its head series contains.