World: r3wp
[!REBOL3]
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BrianH 5-May-2011 [8430x4] | Agreed about this from your example above: >> a: quote (1 + 2) do a == 3 But what I was proposing above was this: >> do 'a == (1 + 2) Would that be acceptable to you? |
Regarding your implementing the first APPLY, that's great. I wish I had seen or heard of your version, so I wouldn't have had to implement the R2/Forward version from scratch. Then maybe we wouldn't have needed the bug fixes that R2's APPLY got later. | |
IIRC, you provided some advice that helped with the R2/Forward version before it got included in R2 the first time. If so, thanks. | |
pretend something is more secure than it actually is - the biggest security concern of R3 is making sure that outside code can't modify the code of functions. There are various tricks that can be done in order to make sure that doesn't happen (putting calls to function values in parens, APPLY, SECURE 'debug). DO of blocks and parens don't need the APPLY or DO in a paren tricks in order to make sure they can't modify the calling code because they can't take parameters, so you can DO blocks and parens without changes to your source code - SECURE 'debug doesn't require changes to source code. This means that less effort is needed to make DO of blocks or parens more secure than DO of functions that can take parameters. The same goes for DO of any non-function type. If you constrain DO of paths or words with functions assigned to them to not be able to take parameters, then they would be exactly as secure as DO of blocks or parens, and can be called with the same code - no additional code wrappers or screening would be needed. This would make DO of words or paths a drop in substitute for DO of blocks or parens. | |
Ladislav 5-May-2011 [8434] | Would that be acceptable to you? - I found out, that everyone except you is against it |
BrianH 5-May-2011 [8435] | No, you found that out about functions, not blocks. |
Ladislav 5-May-2011 [8436] | or, maybe not, we should make another poll |
BrianH 5-May-2011 [8437x2] | Remember, having it evaluate blocks and parens like that would make it not consistent with how words and paths are treated when evaluated inline. |
Consistency was the biggest argument you had for the treatment of word values with functions assigned to them. | |
Ladislav 5-May-2011 [8439] | Well, it looks, that do 'a ; == (1 + 2) may be more convenient |
BrianH 5-May-2011 [8440] | Cool. |
Ladislav 5-May-2011 [8441x3] | (not that I intend to use it frequently) |
It is interesting, that for the case: lit-word: first ['a] do [type? lit-word] we have only two opinions | |
currently, and both prefer the lit-word! datatype as the result | |
BrianH 5-May-2011 [8444x3] | That isn't what you said in #1434 - you said that you would prefer getting the word! type. |
I'm more concerned with people trying to sneak functions into data, which could then use parameters to get access to the original code of another function. This can be used for code injection, or for getting access to bound words that have since been hidden, or to internal contexts. Given that words are often valid data, having a special case where they can execute functions by sneaking in a bound word is a real concern. However, if that function can't take parameters, there is no hacking potential and function code can be secure. The workaround if you don't want any functions executed (beyond the hacking) could be to unbind words retrieved from data, bind them to a known context, or just avoid using DO word or path altogether. | |
As for #1434 (and your most recent code example), I would prefer to have lit-words and lit-paths be consistently active values (the way lit-words are in R3 now) for the same reasons you proposed #1881 and #1882. This means having them convert to word and path when they are evaluated instead of just gotten. But if you would prefer them to be a special case like parens (the way lit-paths are in R3 now), that would work for me too as long as that is the case for both lit-words and lit-paths - it would make them a little easier to work with. | |
Maxim 5-May-2011 [8447] | I'd prefer lit words to be "dead", its so much pain to preserve lit-words within datasets. I've often had "word has no value" errors when building data blocks for dialects or datasets which are being manipulated one way or another . |
BrianH 5-May-2011 [8448] | I meant the "you" in "if you would prefer" to be the collective "you", the consensus opinion, not necessarily that of you in particular, Ladislav :) |
Maxim 5-May-2011 [8449] | ;-) |
BrianH 5-May-2011 [8450] | If lit-words are turned into a special case, being otherwise inactive (like lit-paths are now), that would work for me. Though normally we would want lit-words to be converted to words, if the #1882 change to word evaluation goes through, that would mean that lit-words could change to words which could execute functions. If that kind of thing could happen, I would rather it happen through explicit conversions so you can see it in the code. |
Ladislav 5-May-2011 [8451x3] | in #1434 I did not say anything about my preferences |
I just asked whether a note about "incosistency" contained in there was appropriate | |
not to mention, that the example here is not the example in #1434 | |
BrianH 5-May-2011 [8454] | I guess I had trouble parsing this sentence: I do *not* propose the result of do quote 'a to be a lit-word, since the word really looks reasonable to me. That seemed to be a preference for lit-words converting to words in that case, though I may have misinterpreted that. |
Ladislav 5-May-2011 [8455] | in my opinion, the behaviour of do quote 'a expression is something else than the behaviour of the lit-word: first ['a] do [type? lit-word] example |
BrianH 5-May-2011 [8456x2] | Whether or not there is going to be a difference between inline evaluation of lit-words and evaluation of lit-word values, evaluation of lit-word values needs to be consistent whether you do so by referring to them with an inline word, or through explicit DO. R2's behavior is a bug. |
The choice is between having behavior like what R3's lit-words do now (fully active), or what R3's lit-paths do now (special case for inline evaluation, otherwise inactive). | |
Ladislav 5-May-2011 [8458] | Once again that "consistent" word. There is the main difference. I do not think you can call "inconsistency" any difference in the evaluation of the former and the latter expression, since the former expression is about handling lit-words as arguments of the DO function, while the latter is about handling words as inline block values, when they refer to lit-words. |
BrianH 5-May-2011 [8459] | I've been using the terms inline evaluation for having the value inline in the code, regular evaluation for when the value is referred to through an inline word, and explicit evaluation for when the value is passed to DO directly. If the first is to be different, the latter two need to be consistent with each other, same as with parens. |
Ladislav 5-May-2011 [8460x4] | I intendedly coined the terms active value to refer to a value that when encountered inline in a block does not evaluate to itself word-active value to refer to how a word is evaluated when referring to a value |
These two cannot be "consistent" nor "inconsistent" | |
for example, parens are active, but they are word-inactive | |
(which is conveinient) | |
BrianH 5-May-2011 [8464x2] | OK. There is stuff like functions, and these are called "active values" - they behave consistently for inline, regular or explicit evaluation. There is stuff like parens, which behave one way for inline, and a different way for regular or explicit evaluation - what term would you like to use to refer to this pattern with? Because those are the only two choices that would make sense with lit-words and lit-paths. |
Maxim apparently prefers that lit-words and lit-paths act like parens, and so does Geomol. I would be OK with that model. | |
Ladislav 5-May-2011 [8466] | I prefer that as well |
BrianH 5-May-2011 [8467] | Then please say so in a comment to #1434, so we can have a consensus recorded :) |
Ladislav 5-May-2011 [8468] | OK, I will try |
BrianH 5-May-2011 [8469x2] | Then I can change the "should be" comments in the ticket example code accordingly :) |
The proposed model is something like this: >> 'a/1 == a/1 ; inline evaluation of lit-path converts to path >> b: quote 'a/1 == 'a/1 >> b == 'a/1 ; regular evaluation of lit-path value does not convert to path >> do :b == 'a/1 ; explicit evaluation of lit-path value does not convert to path So it's not exactly like parens, but it's what Maxim, Geomol and I would prefer. | |
Ladislav 5-May-2011 [8471] | Your terminology: inline evaluation regular evaluation and explicit evaluation is acceptable for me (although I am not sure about the "regular evaluation", isn't there a chance to find a better notion?) |
BrianH 5-May-2011 [8472] | I hope so - that term seems to need too much explanation. |
Ladislav 5-May-2011 [8473] | how about "indirect evaluation"? |
BrianH 5-May-2011 [8474] | implicit? |
Ladislav 5-May-2011 [8475x3] | (there is a level of idirection, since an evaluated word refers to a value) |
so, my preferred would be "indirect evaluation" | |
But, again, we actually can see two kinds of indirect evaluation: Inline indirect evaluation , or "explicit indirect evaluation" | |
BrianH 5-May-2011 [8478x2] | Sure. The reason I called it "regular" is because a word! has no markings, either in terms of characters added to the syntax, or qualifiers added to the type name. This implies that word! evaluation is the default, or the regular style, while the others are exceptional. |
:a evaluation is inline too, so "inline indirect evaluation" could apply to that. | |
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