World: r3wp
[Core] Discuss core issues
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Volker 28-May-2005 [1132] | cfor is not only about counting, but about anything like a "step". it may be counting, or stepping through a list by pos: next pos, or whatever. that can't be captured by better hiding. |
Allen 28-May-2005 [1133x2] | Gregg: said "The most common case, by far, is to step by one, so you should be able to omit that IMO. " , for the most common situations, you would use REPEAT or LOOP. I virtually never use FOR, except if I'm thinking in some other language |
for me, FOR is only there when one of the native looping structures doesn't suffice. But I do like then dialect options you present. My pref would be to keep the value outside (to keep closer to foreach syntax)., ie for i [1 to 9 step 2][..] | |
Gregg 28-May-2005 [1135x4] | I rarely use it myself Allen. The only reason I really think it's important at all is that new people coming to REBOL will look for FOR. Need to add a doc section on native verus mezz control functions. |
Volker, it should operate on series values as well, like FOR does today. My examples are all numbers, because that's easier to do concisely. :-) | |
The only time I use FOR today is when I need to: a) start at a number other than 1 b) step by a increment other than one. c) brevity and clarity is more important than performance. | |
If REPEAT had /start and /skip refinements... | |
Romano 28-May-2005 [1139x2] | assume: func [ {If a value is not in a series, append it.} series [series! port!] value ][ any [find series value insert tail series :value] ] |
I propose this new function for Core. check the return values in both cases. | |
ChristianE 28-May-2005 [1141] | As imho is the case with ALTER, ASSUME in my ears sounds too general to give a hint to it's functionality just by it's name. A function like the one you suggest seems very useful to me, though. How's about APPEND-ONCE (could even be APPEND/ONCE on mezzanine level). |
BrianW 29-May-2005 [1142] | I'm losing my mind here ... my Linux rebol scripts just aren't working unless I invoke rebol directly myself. |
Robert 29-May-2005 [1143] | debugging: IIRC I once asked this question already but can't remember the answer. Is it possible from inside a function to get the set-word this code is bound to? I would like to be able to print the set-word for debugging call-traces. |
ChristianE 29-May-2005 [1144x9] | See the following mailing thread: |
http://www.rebol.org/cgi-bin/cgiwrap/rebol/ml-display-thread.r?m=rmlGCNJ | |
You may use a redefined FUNC like | |
func: func [ "Defines a user function with given spec and body." [catch] spec [block!] {Help string (opt) followed by arg words (and opt type and string)} body [block!] "The body block of the function" /name word [word!] ][ either name [ use [self] [ self: word throw-on-error [make function! spec bind body 'self] ] ][ throw-on-error [make function! spec body] ] ] | |
>> a: b: c: func/name [x] [either none? x [print [self "called with X arg of value NONE"]][probe x]] 'my-func | |
>> a 0 0 == 0 | |
>> a none my-func called with X arg of value NONE | |
Might cause serious binding problems, though (I haven't tested it in any serious means). And it may probably not suit your needs exactly. | |
Thought about it twice. Doesn't make any sense, anyway: it has no benefits over printing "MYFUNC called with ..." directly. | |
Ammon 29-May-2005 [1153x2] | Yeah, that's going to have some binding issues. |
But you have the right idea | |
Robert 29-May-2005 [1155] | Ok, than we should add better trace functionallity to Rebol :-)) |
Anton 30-May-2005 [1156] | I agree with Allen, but I would expect FOR to be able to handle variables, eg: for i [1 to 5][ for j [i * 2 to i * 3 step 2][...] ] |
Ammon 31-May-2005 [1157] | What's the trick to getting the @ symbol into your username when checking POP mail in REBOL? |
PeterWood 31-May-2005 [1158x2] | If you check the ML topic index for pop, you'll find http://www.rebol.org/cgi-bin/cgiwrap/rebol/ml-display-thread.r?m=rmlFSJQ http://www.rebol.org/cgi-bin/cgiwrap/rebol/ml-display-thread.r?m=rmlQGBQ http://www.rebol.org/cgi-bin/cgiwrap/rebol/ml-display-thread.r?m=rmlQGBQ Each of which contains the answer. |
Which is : open [ scheme: 'pop user: "[[username-:-coxinet]]" pass: "password" host: "pop.coxmail.com" ] | |
Ammon 31-May-2005 [1160x2] | Yup, found an email you sent to the mailing list referencing this just before you posted here... ;~> |
So you answered my question before I asked it. That's pretty good. ;~> | |
Allen 31-May-2005 [1162] | I'm curios as to why do people use @ in a username.? I thought the rfc said not to. |
Ammon 31-May-2005 [1163] | In this case, ask Google why... |
Graham 31-May-2005 [1164] | It's often because the ISP passes the user onto another pop server ie. the first proxies for the final pop server |
DideC 1-Jun-2005 [1165] | Tiscali has bought many Provider in France. They handle email in @tiscali.fr, @freesbee.fr, infonie.fr ... with the same POP server (proxy?). So they need the full email as login. |
Dockimbel 1-Jun-2005 [1166] | Does anyone know if REBOL runs on Windows CE.NET 4.2 ? I'd need to use REBOL on that platform but I don't have access to a CE.NET terminal and can't use an emulator because there's no REBOL WinCE x86 binary. |
ChristianE 1-Jun-2005 [1167] | This probably is a silly question, but ... What is the benefit of DO GET IN OBJECT WORD over just writing OBJECT/WORD ? I see this a lot in VIEW source (e.g. in DO-FACE) and related guru sources. I really don't see the point of doing so, be there *must* be a reason. Anyone willing to educate me? Is this a path evaluation issue? |
JaimeVargas 1-Jun-2005 [1168] | Maybe the word is dynamic? |
ChristianE 1-Jun-2005 [1169] | Oh, sorry, typo here: should have read DO GET IN OBJECT 'WORD - it's LIT-WORD!, actually. Of course, there *are* differences, e.g. OBJECT/WORD doesn't throw an error if WORD is unset. But I'm uncertain on the exact reason why that idiom is used. |
JaimeVargas 1-Jun-2005 [1170] | Dynamic dispatch of code, if the slot exist. |
ChristianE 1-Jun-2005 [1171] | Still don't get it. Both do-face: func [face value][do get in face 'action face either value [value] [face/data]] do-face: func [face value][face/action face either value [value] [face/data]] seem to work. |
JaimeVargas 1-Jun-2005 [1172x3] | o1: context [ init: [print "Init code for o1"] eval: [print "Eval code for o1"] end: [print "End code for o1"] ] o2: context [ init: [print "Init code for o2"] eval: [print "Eval code for o2"] ] eval-obj: func [obj][ do get in obj 'init do get in obj 'eval do get in obj 'end ] eval-obj o1 eval-obj o2 |
In your example the face may not have an action slot. | |
Therefor throwing an error instead of graceful fail. | |
ChristianE 1-Jun-2005 [1175x2] | Oh, thanks, now it's all clear. I tried with setting WORD to any value I could image, but not with object without WORD. As always, so simple, so obvious! Thanks again. |
Kind of obvious after someone makes it obvious to me, though ;-) | |
JaimeVargas 1-Jun-2005 [1177] | That seems to be the norm with Rebol. But we are so trained to look for complex explanations that we skip the path of less surprise. |
BrianH 1-Jun-2005 [1178] | Plus, the behavior of object/word depends upon what datatype the word is set to and (for some datatypes) which version of REBOL you are running. If WORD is set to a block, OBJECT/WORD is the same as GET IN OBJECT 'WORD, while if WORD is set to a function, or sometimes a path or paren, it means DO GET IN OBJECT 'WORD. By spelling out what you want to do, you won't be as tied to variances in REBOL path evaluation and your code can be more general. |
Gabriele 2-Jun-2005 [1179] | The real reason, most of the times, is what Brian says above: if you want to get a function value instead of evaluating it. |
ChristianE 2-Jun-2005 [1180] | Yes, Gabriele, that's what I supposed it's all about, but since in the places I've seen it, the function weren't used as first class values, but rather evalutated. Jaime pointed me to another reason: the GET IN variant doesn't break if an object doesn't feature the wanted "slot". That really makes sense where code can't be too sure about the objects it handles. Actually, though the guru code I mentioned was some of your changes to the view event- and modal system (I'm still working my way thru it, trying to understand it's pickier details) and other view related code snippets from cyphre, I'd really thought I'd better ask in core group, since it may come down to a more broader misconception of path evalutation I had. I'm happy to see that it's "only" the point Jamie made which I overlooked. |
Gabriele 2-Jun-2005 [1181] | yes, the main point is that you are safer, whatever value is in the object. note that if the word is not available just using get in will break anyway in "older" versions. |
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