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 [1/3] from: ryan::christiansen::intellisol::com at: 15-Mar-2001 16:49

Reading the REBOL/Core manual, I am still uncertain as to what 'set accomplishes. I noticed these two functions in a recent post, one using 'set and the other not using 'set. What does 'set accomplish? exec: func [series [series!]] [ if error? try [return do series] [ join exec_start [series exec_end]]] set 'stringcompose func [ {Evaluates a string of expressions, only evaluating executable parens, and returns a block.} Text [String!]] [ clear buffer parse/all Text rule buffer] Ryan C. Christiansen Web Developer Intellisol International 4733 Amber Valley Parkway Fargo, ND 58104 701-235-3390 ext. 6671 FAX: 701-235-9940 Global Leader in People Performance Software _____________________________________ Confidentiality Notice This message may contain privileged and confidential information. If you think, for any reason, that this message may have been addressed to you in error, you must not disseminate, copy or take any action in reliance on it, and we would ask you to notify us immediately by return email to [ryan--christiansen--intellisol--com]

 [2/3] from: larry:ecotope at: 15-Mar-2001 15:19

Hi Ryan Here is a short answer, others may wish to expand. When issued in the global context, both methods give the same results. But within the block defining an object, they do not:
>> ob: make object! [ f1: func [x][x * x] set 'f2 func [x][x + x]] >> probe ob
make object! [ f1: func [x][x * x] ] ; notice that only f1 is defined within the object, f2 is global
>> f2 4
== 8
>> ob/f1 4
== 16
Using a setword causes the function to be defined within the object. Using the 'set function does not, instead, the word naming the function will be defined in the first ancestor context where it has already been defined, or if the word is previously undefined, in the global context. This behavior of 'set is actually very useful for exporting functions from objects, while in the func definition all of the object vars are available to it. HTH -Larry

 [3/3] from: brett:codeconscious at: 16-Mar-2001 10:27

Hi Ryan A few examples, and explanations. set sets a word to a value
>> set 'myword "test"
== "test"
>> myword
== "test"
>> word-to-set: 'test-word
== test-word
>> set word-to-set 9
== 9
>> test-word
== 9
>> set [w1 w2 w3] 4
== 4
>> w1
== 4
>> w2
== 4
>> w3
== 4
>> set [w1 w2 w3] [1 2 3]
== [1 2 3]
>> w1
== 1
>> w2
== 2
>> w3
== 3 The piece of code you snipped out was part of a larger context - an object.
>> an-object: make object! [
[ name-of-object: "brett" [ function1: does [print ["name of object is" name-of-object]] [ set 'function2 does [ print ["name of the same object" name-of-object]] [ ]
>> an-object/name-of-object
== "brett"
>> an-object/function1
name of object is brett
>> function2
name of the same object brett You can see that function1 and function2 have the same access to the context of the object but function2 is accessed in the global context instead of the context of the object. function1 is a field of the object that is set to a function that was defined within the context of the object. function2 is a word that is set in the global context to a function. This function was defined within the context of the object. So looking back at Marcus' stringcompose! object. The object keeps all the parse rules and supporting functions in a nice tidy bundle. Then by using set Marcus has create a globally available function that uses all the stuff in the object. You don't even need to refer to the object again - it just hangs around holding the bits together for the use of the stringcompose function. So in this case, it doesn't change the functionality of the program, it neatens the structure of the progam. HTH Brett