basics: meaning and uses of make object! vs. context

== "jason"

== [jasonic--nomadics--org]

Q1: Are they different, and if so How? Q2: Why/when/what determines which form to use..? thanks ./Jason

context: func [ "Defines a unique (underived) object." blk [block!] "Object variables and values." ][ make object! blk ] HTH Ammon A short time ago, Jason Cunliffe, sent an email stating:

Merely the amount of typing.

context: func [ "Defines a unique (underived) object." blk [block!] "Object variables and values." ][ make object! blk ] This is another example along the lines of the TO-FOO vs. MAKE FOO thread. -jn-

It had me confused.. it sounded so much more complicated. But that only shows I have not learned to trust SOURCE fully yet. Q1: Are there any situations when source 'someword hides something? [LUKE??] Q2: If CONTEXT is just a typing shortcut, then what are people's preferences for readability, and why? thanks very much ./Jason

make: native [ "Constructs and returns a new value." type [any-type!] "The datatype or example value." spec [any-type!] "The attributes of the new value." ] You see MAKE is a Native! It isn't done in REBOL code, but rather in the language REBOL is written in (C?) so SOURCE couldn't tell you if it wanted to. Other than that, SOURCE will hide nothing from you. Use the SOURCE, Luke! The SOURCE will not fail you... ;-) HTH Ammon A short time ago, Jason Cunliffe, sent an email stating:

Unless it does, of course ...

HI

f: func [][do blk]

** Script Error: blk has no value ** Near: blk This is an artificial example, of course, but it is not that uncommon that critical parts of a function are hidden in an object!. Especially once you start with /View. That said, 'source is always worth a try. Kind regards, Ingo

Of course, given Rebols inspection abilities, you _can_ get to the source:

== [do blk]

== blk

== [print "HI"] Sometimes you need to dig a little ... Kind regards, Ingo

Hi

f: func [][do blk] The little bit above is an actual cut and paste from a fresh REBOL/Command console on Linux RedHat 7.2 if you actually get something different somewhere else please let us know. 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)

== [print 'Hi]

f: func [][do blk]

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. 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.

[ print "making a" ; this line will be lost [ a: does [print "making a"] ;this will not [ ] making a

a: make object! [ a: func [][print "making a"] ]

== { make object! [ a: func [][print "making a"] ]}

== "?object?"

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! HTH Ammon PS thanks to your post, I found that you can create a global word that has a context different than the global context without using 'bind! Enjoy!! A short time ago, Ingo Hohmann, sent an email stating:

<..>

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:

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.

<..>

Then, have you tried to 'source the 'a object! from above?

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.

[print "Hi"] Thanks!! Ammon A short time ago, Ingo Hohmann, sent an email stating: