red/help

For help with your code, suggestions and ideas, and learning Red.

Toomas Vooglaid

@toomasv

@GiuseppeChillemi Or, if you have bound words somewhere else, e.g.:

a: [b]
o: object [b: 2]
bind a o
context? a/1
;== make object! [
;    b: 2
;]

GiuseppeChillemi

@GiuseppeChillemi

@toomasv Yesterday it was too late. I was using PRINT instead of PROBE to get the context.

Boleslav Březovský

@rebolek

Careful with that, print evaluates

GiuseppeChillemi

@GiuseppeChillemi

@toomasv I still not undestand how to get the context of a word inside a block.

@rebolek Yes, I have discovered it with long consolle output !

Toomas Vooglaid

@toomasv

@GiuseppeChillemi If you have bound words in the block, you can ask context? of these words, as in above example.

Also:

>> a: [context? 'b]
== [context? 'b]
>> o: object [b: 2]
== make object! [
    b: 2
]
>> bind a o
== [context? 'b]
>> do a
== make object! [
    b: 2
]

Greg T

@gltewalt

If you’re wondering how to get the name that a value is set to... values are anonymous.

nedzadarek

@nedzadarek

@GiuseppeChillemi to add to @toomasv answer:
you just need to extract a word!. As Toomas noted, you can use /n syntax (arr: [a b c] arr/3; c) or using pick (pick [a b c] 3). You can evenfindit (first find [a b c] 'a`). As fair I remember, it's like any other way to extract values.

@toomasv has binding changed? I remember saving bindings (e.g. arr: [a b c] arr: bind arr context [a: 1 b: 2 c: 3]). I don't think it's necessary now.

Toomas Vooglaid

@toomasv

@nedzadarek No need to "save". Bindings are changed in-place. But you can bind a (deep) copy with bind/copy.

nedzadarek

@nedzadarek

@toomasv I see.
@toomasv @GiuseppeChillemi As fair I know bind binds any-word!:

>> arr: [a a: 'a :a] 
== [a a: 'a :a]
>> reduce to-word probe first (bind arr context [a: 42])
a
== 42
>> reduce to-word probe second (bind arr context [a: 42])
a:
== 42
>> reduce to-word probe third (bind arr context [a: 42])
'a
== 42
>> reduce to-word probe fourth (bind arr context [a: 42])
:a
== 42

GiuseppeChillemi

@GiuseppeChillemi

Here:

y: [b c d]
probe context? y/1

I expected a result from context? but basically I was wrong. I supposed B has some context

Boleslav Březovský

@rebolek

But there is result.

Also,

>> equal? system/words context? y/1
== true

nedzadarek

@nedzadarek

@GiuseppeChillemi don't probe it - main context is huge to print

GiuseppeChillemi

@GiuseppeChillemi

@rebolek , yes there is a result.

Also I expected a result from:

z: make object! [b: 0 c: 1 d: 2]
probe context? z/1

But I get an error

*** Script Error: cannot access 1 in path z/1
*** Where: context?
*** Stack: probe 
>>

Boleslav Březovský

@rebolek

z is object, there's no z/1

this has nothing to do with context?

GiuseppeChillemi

@GiuseppeChillemi

@gltewalt

If you’re wondering how to get the name that a value is set to... values are anonymous.

This is now clear to me.

@rebolek I expected z/1 returning the first word in the object and returning the object Z itself as result of context?

nedzadarek

@nedzadarek

@GiuseppeChillemi I guess you have used the Rebol to have such expectations:

z: object [a: 1 b: 2]
first z
; == [self a b]
second z
;== [make object! [
;        a: 1
;        b: 2
;    ] 1 2]

Boleslav Březovský

@rebolek

@nedzadarek certainly not, first z does return words-of, not first word.

@GiuseppeChillemi Ah, you wanted this:

>> z: make object! [b: 0 c: 1 d: 2]
== make object! [
    b: 0
    c: 1
    d: 2
]
>> w: words-of z
== [b c d]
>> w/1
== b
>> context? w/1
== make object! [
    b: 0
    c: 1
    d: 2
]

nedzadarek

@nedzadarek

@rebolek

@nedzadarek certainly not, first z does return words-of, not first word.

I mean that only the Rebol allows you to use integer indexes (well, first and second) to retrieve words & values respectively. The Red is more descriptive (-of functions).

Boleslav Březovský

@rebolek

@nedzadarek right, it does, however @GiuseppeChillemi writes: I expected z/1 returning the first word in the object..., so this has nothing to do with first and second (and third also, IIRC) functionality in Rebol.

nedzadarek

@nedzadarek

@rebolek Maybe he saw obj: make object! [...] ... second obj. So, he thought "I can use integer indexes on objects".

After some time he tried it on the Red (not remembering exact details), expecting above.

Boleslav Březovský

@rebolek

GiuseppeChillemi

@GiuseppeChillemi

Yes, when I see a block I think automatically I can get its elements via integers

Boleslav Březovský

@rebolek

And you of course can. However, object is not a block.

GiuseppeChillemi

@GiuseppeChillemi

I always think that there is an uniform access method in RED or REBOL so I apply the knoledge of blocks in object as when I probe them they actually seem an block with a "make object!" just before.

It's common to abstract a rule and apply it on similar things.

But REDBOL has many so many changes that this method can't be always applied.

Boleslav Březovský

@rebolek

There's no literal form of object which may be confusing for some people. But have a look at map!, it has its literal form - #( ... ), so you can't confuse it with block, can you? And objects are more like maps in this regards.

GiuseppeChillemi

@GiuseppeChillemi

However I think that having uniform access methods make easier to handle the language.

I don't know what you mean for "literal form" but I can imagine

Boleslav Březovský

@rebolek

There is uniform access method in form of path: x/y/z, but that does not mean that you can use integers everywhere, only where appropriate.

Max

@moliad

objects have little to do with blocks. objects are not series.

Boleslav Březovský

@rebolek

Literal form is datatype specific syntax.

Map has one, object doesn't.

GiuseppeChillemi

@GiuseppeChillemi

Yes @moliad but first/second/third or obj/1 ../2 /3 is a method you could apply to object content. In fact in rebol you could use it on the third element of an object. (i.e.: probe first third obj)

Vladimir Vasilyev

@9214

@GiuseppeChillemi because third obj in Rebol is equivalent to body-of obj in Red.

GiuseppeChillemi

@GiuseppeChillemi

So, having

z: make object! [b: 0 c: 1 d: 2]

a first z returning b could be a valid access method.

@9214 Yes, now I have understood

In RED a more explicit and verbose method is used

Max

@moliad

@GiuseppeChillemi in fact /1 /2 /3 doesn't work in Rebol :smirk:

>> a: context [a: 8]
>> a/1
** Script Error: Invalid path value: 1
** Near: a/1

GiuseppeChillemi

@GiuseppeChillemi

Just had to learn the proper way to get object contend

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