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[REBOL] Re: basics: meaning and uses of make object! vs. context

From: ingo:2b1 at: 11-Jun-2002 19:30

Hi Ammon, Ammon Johnson wrote:
>>>a: make object! [ blk: [print 'Hi] set 'f func [] [do blk]] >>>f >> > Hi > >>>source f >> > f: func [][do blk] >
> I don't see what you are talking about, I didn't see any lost code. Source > delivered to you EXACTLY what you asked for, the very source of 'f. What is > the difference between the example above and the example below? (again this > is from a fresh console) > >>>set 'f func [] [do blk] >>>blk: [print 'Hi] >> > == [print 'Hi] > >>>source f >> > f: func [][do blk] > >>>f >> > Hi > > basically nothing. In the previous example the Global word 'f was set when > the spec block of 'a was evaluated by 'make. In this example f was set at > the commandline. The reason that 'f does the value of a/blk in your example > is because 'f was created in the *context* of a, or in other words the words > within the 'a object are *local* to 'f. I am not sure what you were > expecting to see when you typed "source f" at the commandline, but you saw > the actual source of 'f.
You are right, there is no _basic_ difference, between the two. What I wanted to illustrate is, that you can't understand what 'f is doing, without knowing the content of 'blk. And the content of 'blk, in my example, is hidden in a different context, so 'source won't tell you about it. A real world example:
>> source request-date
request-date: func ["Requests a date." /offset xy][ if none? base [init] either offset [inform/offset date-lay xy] [inform date-lay] base ] Can you tell me what this function will be doing, from viewing the 'source output, alone? I guess not.
> That said, I think that what you are refering to is the fact that when you > pass a block to make as you did in your example the block is evaluated and > any commands given are done, any values that are not assigned to words with > in the spec block are lost for example. > >>>a: make object! [ >> > [ print "making a" ; this line will be lost > [ a: does [print "making a"] ;this will not > [ ] > making a > >>>source a >> > a: > make object! [ > a: func [][print "making a"] > ] >
> Do you see what I am saying? SOURCE will even give you the the very SOURCE > of an Object! (something I wasn't fully aware of) Go ahead, use the SOURCE > faithfully it. It will not fail you LUKE!
Then, have you tried to 'source the 'a object! from above?
>> source a
a: make object! [ blk: [print 'Hi] ] (or probe, or whatever ...) Sometimes theres more to the SOURCE than meets the eye :o) Ingo P.S: probe req-funcs/reg-date ;to get the missing link for request-date.