World: r3wp
[!REBOL3]
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Ladislav 30-Apr-2011 [8311x2] | I prefer the latter |
(seeing it as more convenient) | |
GrahamC 30-Apr-2011 [8313] | latter |
Ladislav 30-Apr-2011 [8314x2] | And, how many users prefer: a: make object! [b: does ["OK"]] type? do in a 'b ; == function! versus a: make object! [b: does ["OK"]] type? do in a 'b ; == string! |
I prefer the latter again | |
PeterWood 30-Apr-2011 [8316] | The latters seems more logical to me in both cases. |
Geomol 30-Apr-2011 [8317x2] | The latters seems ok to me. But what if w is a word holding 'b or 'a/b, as I was testing, in relation to the object a? This is what I get: In R2: >> a: make object! [b: does ["OK"]] >> w: first ['b] == 'b >> type? :w == lit-word! >> a/:w ** Script Error: Invalid path value: b ; To me, that error is wrong worded, it should show 'b. >> in a :w == 'b ; Confused, as a doesn't hold any 'b >> do in a :w == 'b ; Why? >> type? do in a :w == lit-word! Same in R3: >> w: first ['b] == 'b >> type? :w == lit-word! >> a/:w ** Script error: cannot access :w in path a/:w ; Not sure about this error. Could be better, I think. >> in a :w == 'b ; ? >> do in a :w == b ; ?? >> type? do in a :w == word! |
And now the 'a/b: In R2: >> a: make object! [b: does ["OK"]] >> w: first ['a/b] == 'a/b >> do w == "OK" >> do :w == 'a/b In R3: >> a: make object! [b: does ["OK"]] >> w: first ['a/b] == 'a/b >> do w == 'a/b >> do :w == 'a/b | |
Maxim 30-Apr-2011 [8319] | wrt: And, how many users prefer: a: make object! [b: does ["OK"]] type? do in a 'b ; == function! versus a: make object! [b: does ["OK"]] type? do in a 'b ; == string! ============================ the first should be supported via the 'GET word, so I'd say the later is better, otherwise, there is no point with 'GET. basically, this was perfect in R2, why did it change in R3? |
onetom 30-Apr-2011 [8320] | seems like a bug |
BrianH 1-May-2011 [8321x2] | It changed because functions were getting executed when you were doing a word referring to a function, rather than doing the function itself. |
Ladislav, that ticket was related because it explained that lit-words were active values and that the behavior was intentional. This can be changed if we decide differently, but it isn't currently a bug, it's intentional. | |
Ladislav 1-May-2011 [8323x2] | I understand that the change was intended, but currently, all the respondents prefer the original behaviour. |
And no wonder they do. If a user calls the DO function, then it is expectable that functions, etc. get evaluated. | |
BrianH 1-May-2011 [8325x2] | Yes. But that is doing the *function*, not doing a word that refers to the function. |
It's the difference between a: :print and a: 'print. | |
Ladislav 1-May-2011 [8327] | As said, all the respondents above prefer the function to be evaluated when doing a word that refers to the function. The only way how you can influence it would be if you said you preferred the current behaviour as implemented in R3. Do you? |
BrianH 1-May-2011 [8328] | For that, absolutely. For the lit-word/lit-path thing, no. |
Ladislav 1-May-2011 [8329] | I hope we get more answers, since it is weekend now. |
Ladislav 3-May-2011 [8330x6] | http://issue.cc/r3/1881and http://issue.cc/r3/1882submitted |
Regarding the example evaluating words above: lit-path: first ['a(b] do [lype? lit-path] Which result do you prefer? As far as my preferences go, I prefer to obtain the lit-path! datatype | |
Correction: Regarding the example evaluating words above: lit-path: first ['a/b] do [type? lit-path] Which result do you prefer? As far as my preferences go, I prefer to obtain the lit-path! datatypeRegarding the example evaluating words above: lit-path: first ['a(b] do [lype? lit-path] Which result do you prefer? As far as my preferences go, I prefer to obtain the lit-path! datatype lit-path: first ['a/b] do [lype? lit-path] | |
This keyboard is getting me crazy, sorry | |
Correction: Regarding the example evaluating words above: lit-path: first ['a/b] do [type? lit-path] Which result do you prefer? As far as my preferences go, I prefer to obtain the lit-path! datatype | |
(in R3 yout get the lit-path!, while in R2 the path! datatype) | |
Geomol 3-May-2011 [8336] | I prefer lit-path!. The same for lit-words: lit-word: first ['a] do [type? lit-word] I prefer that to return lit-word!. It's only, if the word being looked up (lit-word in this example) is a function (or native, op, action, ...) that further computation should occur, I think. |
Ladislav 3-May-2011 [8337] | Makes sense |
Geomol 3-May-2011 [8338x2] | Actually I ran into problems related to this, when programming the bparse function. At one point, I need to test, if a token variable is equal to the word END. To specify the word END, I write it as a lit-word, because lit-words are changed to words on the run. I need to use == to compare, because I want the type to be the same too. So I would expect, this is the correct test: token == 'end Let's test: >> token: first [end] == end >> token == 'end == true Seems to work, but then the surprise, if token is a lit-word: >> token: first ['end] == 'end >> token == 'end == true Also true? Hmm, so I have to write: >> :token == 'end == false |
The above is done in R2. | |
BrianH 3-May-2011 [8340x6] | Strangely enough, with http://issue.cc/r3/1882you are proposing to do the opposite of http://issue.cc/r3/1881 |
In #1881 you are proposing to take what in R3 is currently an active value and render it inactive, which will make it mildly safer to handle - lit-word/lit-path conversion to word/path is a trivial thing. In #1882 you are proposing to make the word! type into an active value, where you would have to treat every word value as carefully as you treat the function it is assigned. Except it's worse, because in R2 it has the effect of doing *blocks* as well, if those blocks are assigned to a word - even DO of an inline word isn't that unsafe. It is really bad. | |
Please, be consistent here. If you accept #1881, please reject #1882, for our own safety. | |
Oh wait, I misread #1881, I thought it was the lit-path thing. Never mind, it's unsafe too. | |
I noticed when you did the poll, you used a safe function that you knew the source of. Do the poll again with a function that deletes your hard drive, or even a block of code for some other dialect that will coincidentally do damage when interpreted by the DO dialect (since R2 does this with blocks and parens as well). Or even a function that takes an unknown number of parameters, and put the call in the middle of code that might be affected by evaluation order or get-word hacking. | |
Most of you might not remember this, but parens used to be treated as active values in R2. If you had a paren assigned to a word, putting that word inline in a DO dialect block would cause the paren to be executed. I used to use this as a way of having quick thunks (functions that take no parameters) without calling DO explicitly. However, this made it difficult to work with paren values, and was eventually removed for security reasons because it made screening for potentially dangerous values more difficult than a simple ANY-FUNCTION? call. It would be bad to make word! and path! values just as difficult to work with. | |
Ladislav 3-May-2011 [8346] | In #1881 you are proposing to take what in R3 is currently an active value and render it inactive - do I? |
BrianH 3-May-2011 [8347x3] | No, I mistokk what you were saying, and corrected myself in the "Oh wait" message. |
#1434, #1881 and #1882 now have clarifying comments. | |
Btw, this comment in #1882: "and since you've requested that lit-word! and lit-path! be returned to their R2-style inconsistency" may not be an accurate representation of your proposal (here earlier in conversation). You might be proposing that R3 do a better job at being inconsistent than R2 is doing (as demonstrated in #1434). If so, cool. | |
Gregg 3-May-2011 [8350] | I prefer convenience, but understand the concerns about security. Less aggressive evaluation by DO doesn't solve the security problem though, does it? If we say "Never DO untrusted data", DO can provide more convenience. Of course, that means it may be less convenient if you have to evaluate untrusted data, but at least the line is clear. |
Geomol 3-May-2011 [8351] | >> o: make object! [f: does [42]] >> do in o 'f ; This is a problem, as nothing seems to be happening! >> o/f == 42 I'm not sure, I understand the security concern. |
Ladislav 4-May-2011 [8352x3] | Frankly, there is no security problem which can be influenced by this. |
Stating otherwise is just pretending | |
If somebody wants to use DO, he is responsible for knowing what he is doing | |
BrianH 4-May-2011 [8355x2] | Pretending that security doesn't matter is a worse policy. Here is what would resolve the security issue: - Putting warnings in the docs for DO, in the same section where they talk about the special treatment of functions and blocks. - Make parameters not work, and don't do blocks and parens through word values, same as R2's DO of path values. - Make sute that we don't try to make set-words and set-paths do assignment when you DO them. Treat them like get-words and get-paths. Together, those restrictions would make DO of word and path values no more insecure than DO of block and paren values. For functions, we have APPLY. |
sute -> sure | |
Maxim 4-May-2011 [8357] | btw, I've been using apply in R2.7.8 and it works really well :-) |
BrianH 4-May-2011 [8358] | DO of block and paren values is something that we can say is secure enough already, assuming that variables and such are protected and secured, so that is a good set of restrictions to follow for words and paths. Calling functions through inline words is secure enough if you can control the binding and writeablility of those words. DO of function values has the argument problem, but it's known and has built-in workarounds (APPLY, putting function calls in parens), and we already have simple ways to screen for them. |
Gregg 4-May-2011 [8359x2] | DO is seductive, because sometimes I want to create (easily) a "dialect environment" and just use DO to evaluate my dialect., safely and securely. Is there a security page in the docs (I don't see one in the R3 docs right now)? If not, that would be good to have. If we have a list of functions and operations you shouldn't use on untrusted data, and what the risks are, that's a good start. |
And, as Brian mentions, having workarounds or being able to screen for exploitable features. | |
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