World: r3wp
[!REBOL3]
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Jerry 28-Sep-2011 [9562] | I might be able to do that as a by-product of learning R3 module. |
BrianH 28-Sep-2011 [9563] | Cool. I'll remember you said that :) |
Jerry 28-Sep-2011 [9564x2] | I have 10 days vacation, I am totally free before Oct 9th. I plan to read the R3 source code and refactoring my Translation Engine which was written in R3. |
But as you can see, my Enginsh might not be good enough. That's the only thing that I worried about. | |
BrianH 28-Sep-2011 [9566] | That might not be a problem - I am a better editor than a writer. |
Jerry 28-Sep-2011 [9567] | BrianH, I will send you a R3-Module Doc after my vacation for you to correct. Actually, I was a technical Editor in O'Reilly Taiwan. Of course, The books that I edited were all in Chinese. |
Sunanda 29-Sep-2011 [9568] | Question for Carl? :) http://stackoverflow.com/questions/7577186/is-rebol-still-alive |
Jerry 4-Oct-2011 [9569] | I've read info out R3 Module Details from DocBase, R3 Blog and its comments, and source code. Many pieces of info are conflicted. It's annoying. |
BrianH 4-Oct-2011 [9570x3] | Yup. The source code represents the current intended design, though one question has popped up recently that didn't arise during the design process. The !REBOL3 Modules group here has a lot of info too. I hope to get the chance soon to go over the docs on rebol.net and update them to the latest design. I was going to do that last weekend, but I got really sick. However, I am using REBOL at work now for utilities, so I can afford to work on it again here and there. |
I find that the source and the !REBOL3 Modules group are the best places to look for now if you want low-level docs and usage tips. | |
Andreas asked a lot of good questions :) | |
Jerry 4-Oct-2011 [9573] | OK. Thanks BrianH. Take care of yourself. |
Ladislav 8-Oct-2011 [9574x3] | Brian, regarding BIND, I mean e.g. this: >> f: make function! compose/only [[a b c](body: [a do c])] >> a: first body == a >> f 1 1 [a + b] ** Script error: b has no value ** Where: do f ** Near: do c >> f 1 1 bind [a + b] first body ** Script error: none word is not bound to a context ** Where: bind ** Near: bind [a + b] first body |
That is annoying, since it is actually false | |
here is how I can circumvent it: | |
BrianH 8-Oct-2011 [9577] | The 'b in that case is just data, not the argument b. It's another word which has the same name but a different context. |
Ladislav 8-Oct-2011 [9578x2] | yes, that is the unbound block, that does not matter |
here is a way how I can circumvent it: f 1 1 change [a] first body | |
BrianH 8-Oct-2011 [9580] | Yeah, it is an interesting efficiency hack that MAKE function! does a BIND on the function body instead of a BIND/copy. It does mean that you need to be careful with the runtime accessibility of your source though. |
Ladislav 8-Oct-2011 [9581x2] | MAKE function! does a BIND on the function body instead of a BIND/copy - it is not only for efficiency, it is actually the proper way even for safety |
I do like that. but, nevertheless, the MAKE function is able to bind, while I am not, which proves, that it is just an artificial, (not making anything more secure) and annoying limitation | |
BrianH 8-Oct-2011 [9583] | it is actually the proper way even for safety - Why so? Once the function is made, security dictates that the accessibility of its bound body should be limited. If you can get a bound body, you can trace through the bindings to get access to any internal code it references. That is why R3's BODY-OF does something like an UNBIND/deep COPY/deep. If MAKE function! does a BIND rather than a BIND/copy, that means that any extant references to the original body block argument are a potential security hole unless they are contained. |
Ladislav 8-Oct-2011 [9584] | security dictates that the accessibility of its bound body should be limited - yes, and it normally is For that it suffices for you to use the FUNC function, and, voila, you are safe. |
BrianH 8-Oct-2011 [9585] | Yes, we've made other functions help work around the potential security weakness of MAKE function! - that's the tradeoff we made for efficiency. And as long as you either use COPY/deep generators like FUNC, or control the accessibility of your source, it's a really good tradeoff. |
Ladislav 8-Oct-2011 [9586] | Well, for me, that is better than the R2 approach, where it actually is the other way around, i.e. insecure. |
BrianH 8-Oct-2011 [9587] | Definitely. Sometimes it's hard to go back to R2 after programming in R3 - you get spoiled by the advantages. |
Ladislav 8-Oct-2011 [9588x4] | But, that does not solve the BIND annoyance. |
In my opinion, BIND should simply obey and not annoy with error message in such a case | |
As said, if BIND does not do it for me, I can do it on my own using CHANGE, so no safety can be gained | |
...and, CHANGE actually isn't the only method usable, there are other, even uglier methods | |
BrianH 8-Oct-2011 [9592x2] | You can do it with CHANGE only if you get access to the bound body block, which is why letting a reference to that out is a security hole. |
Or to a bound word. | |
Ladislav 8-Oct-2011 [9594] | Yes, understood, but that is fine. I know what I am doing and arrange the security as I see fit |
BrianH 8-Oct-2011 [9595] | On second thought, allowing BIND to take a function! for its context argument would allow you to get around the security protections of BODY-OF. |
Ladislav 8-Oct-2011 [9596x2] | I do not want to do that with a function. It really suffices to do it with a word |
And, besides, it is circumventable anyway, the only reason why I do not show you that alternative is, that it looks even uglier than the usage of CHANGE | |
BrianH 8-Oct-2011 [9598] | But you can already BIND to a word bound to a function context. BODY-OF just keeps you from getting access to a word bound to a function context from outside the function. As long as you control access to the original code block you are secure. |
Ladislav 8-Oct-2011 [9599x2] | But you can already BIND to a word bound to a function context. - actually, I cannot, if the function isn't already running (in that case BIND refuses to do that) |
That is what I call "annoying" | |
BrianH 8-Oct-2011 [9601] | >> bind 'a do func [/a] ['a] ** Script error: a is not in the specified context ** Where: bind ** Near: bind 'a do func [/a] ['a] Well, then you don't have to be as careful with letting bound function words leak I guess. |
Ladislav 8-Oct-2011 [9602x3] | (since it does not enhance security in any way) |
But, that is wrong, since when you let the word out, you can bind, just not using the BIND function (you need to use CHANGE for that) | |
or, having the access to the body, you can do other tricks | |
BrianH 8-Oct-2011 [9605] | That isn't binding, that is changing to a word that is already bound. |
Ladislav 8-Oct-2011 [9606x2] | And what else binding is in this case? |
Binding just replaces all the words it "binds" | |
BrianH 8-Oct-2011 [9608] | >> head change [1] 'a == [a] >> head change [1] #"a" == [#"a"] With BIND, you can leak the 'a word and get access to the 'b word from that same context. You can't do that with CHANGE. |
Ladislav 8-Oct-2011 [9609x3] | yes, but that is not a safety measure. |
That is only "false safety", since it is circumventable | |
As long as you "Leak out" one word, you actually leak out the whole context, just not for the people who don't want to use "dirty tricks" | |
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