World: r3wp
[!REBOL3]
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BrianH 25-Mar-2010 [1855] | I only need to bind blocks differently to the same context *when I tell it to do so* (aka, when solicited). This is so I can write code that expects 'self to be bound without having to check whether the object I am binding to has the hidden 'self field. If I had to check for that, I would have to do that check with every usage of BIND where I had a 'self reference and use different code blocks depending on the results of that check. It is much better for BIND to just do what I tell it to do. |
Ladislav 25-Mar-2010 [1856] | Regarding the Steeve's point: as far as I am concerned, your suggestion *is* consistent. (I see it as more consistent, than the current state) The only problem with it is, that some users may find it uncomfortable, since they do not need to have 'self related to e.g. Repeat, or other cycle functions... |
BrianH 25-Mar-2010 [1857x2] | Ah, but that's a separate issue than the BIND/self vs. BIND/no-self thing. BIND already has the option, internally, accessible by native code, to not unhide and bind 'self. And the loop functions can already use that option, and should: They shouldn't override 'self bindings unless 'self has been overriden with another, unhidden 'self field. |
I definitely agree with that one :) | |
Ladislav 25-Mar-2010 [1859] | People who need the 'self binding sometimes with a context, and don't need it other times with *the same context*. - please, exclude me from the set of People, then. |
BrianH 25-Mar-2010 [1860] | Sure. That's why we have options :) |
Steeve 25-Mar-2010 [1861] | too late Ladislav, your "self" is already bound |
Ladislav 25-Mar-2010 [1862x2] | LOL |
...nevertheless, I need not worry, since there is an option... | |
BrianH 25-Mar-2010 [1864x3] | And note that the 'self trick only applies to the special hidden 'self field. And overrides of that field aren't affected: They will be bound or not, normally, depending on whether they are themselves hidden. And BIND/self shouldn't show a overriden 'self field if it is hidden - it should show the original 'self. Does that make sense? |
And overrides -> Any overrides | |
Hidden fields are weird. | |
Steeve 25-Mar-2010 [1867] | Well Brian, Your words have no self meanings outside this discussion either |
BrianH 25-Mar-2010 [1868] | Very existential of you: self has no meaning :) |
Steeve 25-Mar-2010 [1869x2] | until it's bound to something |
to a context for instance | |
BrianH 25-Mar-2010 [1871] | I feel like that sometimes whenever I'm single. |
Steeve 25-Mar-2010 [1872] | too selfish :) |
BrianH 25-Mar-2010 [1873x2] | The funny part of all this is that if the "hidden 'self field" is mandatory and not modifiable, R3 doesn't necessarily have to have a physical field to store it: It could be implicit. It's just a matter of whether having the physical field there is more efficient to implement than an implicit field (which I suspect it is). |
Oh, Ladislav, you're going to hate this worse that THROW not throwing: What we call "contexts" in REBOL aren't contextual :) | |
Steeve 25-Mar-2010 [1875] | well in R2 it is explicit and modifiable |
BrianH 25-Mar-2010 [1876x2] | well in R2 it is explicit and modifiable And a security hole because of this. |
(Did I just say that out loud? Stupid web-public groups.) | |
Steeve 25-Mar-2010 [1878] | I must admit, I don't really understant that claim. Why is it a security hole ? |
BrianH 25-Mar-2010 [1879x2] | Because 'self is *used*, by code that expects it to refer to the same object that it is bound to. So if it is changed to refer to another object, that code fails. And if that change of referent is carefully done on purpose it can break the code in ways that it wouldn't detect. And that can be bad in some cases. Admittedly, it's not a big hole. BIND? doesn't have this problem: It doesn't return self, it returns the real context reference. |
BIND? was originally added to R2 to deal with that security problem - we used to use 'self more often. And in R3 the 'self is protected, and not unprotectable by UNPROTECT in a special case. So it's not just BIND that special-cases 'self. | |
Ladislav 25-Mar-2010 [1881] | And once the context is created and extends beyond the function of its initial creation, there is no standard for which is more common. - actually, there is a standard, successfully used in R2: always do the same, which is both consistent and "what is needed", since that is, what the programmer asked for |
Steeve 25-Mar-2010 [1882] | Amen |
BrianH 25-Mar-2010 [1883] | Ah, but in R2 those contexts were broken when they extended beyond the life of the function that created them. The first field was treated like 'self, and hidden. |
Steeve 25-Mar-2010 [1884] | I like reading the scriptures. The Gospel according to St. Ladislav. |
BrianH 25-Mar-2010 [1885x5] | And the programmer that matters when it comes to BIND is the one that is calling BIND, and providing the code block. Not the one that made the context. It's different with internal use of BIND, functions that make, use and discard a context. If the context persists then it needs to behave in a predictable matter. R2 is not a good example to cite when deciding what is good coding practices; we made the decision to change things in R3 for *many* good reasons. |
If the context persists then it needs to behave in a predictable matter. - and I mean predictable by someone who didn't make the context in the first place. | |
Otherwise we won't be able to write generic code that works with all contexts. | |
And once again, I regret that we decided to use the term "context" so badly here in the REBOL community. It's really inappropriate. | |
It's much better to call them objects; the Lisp community calls them environments. | |
Ladislav 25-Mar-2010 [1890x3] | And the programmer that matters when it comes to BIND is the one that is calling BIND, and providing the code block. Not the one that made the context. - this is interesting, again. My note is, that if the context was created to support e.g. the functionality of For, then any subsequent binding is meaningful for me, only if the functionality remains supported. I think this way, even when I am the one calling Bind and providing the block, unfortunately, I may not know, which alternative mentioned by you to use, not knowing the type of the context I obtained. As opposed to that, when I see a context without 'self, I know, that the context was created so, that it is not meant to support 'self binding, and that is all I need to know. How would you do it obtaining a context of unknown origin, that would contain '"unsolicited" self? (of course, not knowing that information, since there is no way how you can find that out) |
I meant the above as a contribution to the "predictability" issue - how can you predict, whether the block would behave as originally intended, not knowing, what the original intent was? | |
(unfortunately, the same objection applies to #1544, since then, again, "the original intent" is lost) | |
BrianH 25-Mar-2010 [1893x2] | Generic functions that work on objects don't see the code that originated them. They can only tell how the objects are supposed to behave with their own code. Original intent was contextual (using the term correctly this time). Current behavior is a different context. |
It's like that quote from The Incredibles: "I know what I said before! Listen to what I'm saying *now*." | |
Ladislav 25-Mar-2010 [1895] | I provided above a specific example, that demonstratd clearly what I meant. The support for code like that is missing in R3 and remains missing, even if any of #1544 or #1543 will be accepted. |
BrianH 25-Mar-2010 [1896x3] | What you want is for objects created by loops and functions for their local variables, but persisting after their creators are finished with them, to *break* all other code that expects objects to behave like objects. Same as in R2. It was a bad idea in R2 (which we can't fix) and it's a bad idea in R3. |
This is what we get for calling objects "contexts": It makes us think they are contextual, when they aren't. | |
If you don't like the hidden 'self field in objects in R3, fine, but it was a fix to major problems in R2. Problems we don't want to come back. | |
Ladislav 25-Mar-2010 [1899x2] | ...to *break* all other code that expects objects to behave like objects... - this has been demonstrated by Andreas to be false - I do not want to break any behaviour of objects, I do want to not break behaviour of other contexts than objects |
...and, besides, my code example above is not of the kind "after their creators are finished with them" | |
BrianH 25-Mar-2010 [1901] | Only the function! type creates other "contexts" than objects: It creates a stack-relative objects. All other contexts *are* objects, internally. Even those used by closures and loop functions. There is no difference. |
Ladislav 25-Mar-2010 [1902] | yes, harm already done, the closure, For, Use, Repeat, Foreach, etc. contexts already broken |
BrianH 25-Mar-2010 [1903] | They were broken in R2. Problem solved for R3 - we just have to manage the binding trick. |
Ladislav 25-Mar-2010 [1904] | as demonstrated by my code, already broken, my code works in R2 |
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