5 - Forth Interest Group

More documents

Recommendations

Info

(GEnie/nrm pago 32.) not endorse, and never have endorsed, the approach that has been taken in this area by the ANSI team. I felt that, in this case, an attempt was made, profbmra, to consult me. I thank Mitch Bradley for at least making an effort to hear different opinions before taking . . . action. From: Greg Bailey In reply to John Wavrik's recent postings regarding the discussion that has followed his " d i s e post- ~ ~ ing: First, I should like to apologize to Dr. Wavrik for having misunderstood his intentions in re-posting his architecture article. It was dated 19 Aug., appeared on GEnie 20 Aug., and, given its wording ("this may be the best general response"), it seemed to me that this was the totality of his response. Since a more specific response appeared on GEnie five days later, I clearly misunderstood his intent. Second, I should like to apologize to Dr. Wavrik if I have put any words into his mouth. On the other hand, it is diffimlt to discuss the positions taken by another without restating them somewhere along the line; and since obviously such restatements are not in the other party's words, it would seem that the same could be said of any rebuttal delivered by anyone. However, if my restatement of what John appeats to be saying is grossly at conflict with his meaning, I am glad to be shown what the meaning really is. In fairness, however, one major reason for replying to John's postings is that he is articulate and seems to me to have put many words into the mouths of the TC. For example, John has drawn the following erroneous interpretations of just several recently made points: "GB's.. . comments illustrate the faa that there are also people in the Forth Figure Ten. User-level view of window code. I METHODNAME CLEAR METHODNAME DISPLAY METHODNAME SCROLLUP METHODNAME SCROLLDOWN METHODNAME >XY CLASS WINDOW ( xlr ylr xu1 yul -- ) DATA , \ Rectangle \ Plus additional attributes internal to window operations METHODS CLEAR M: ... M; DRAW M: ... M; SCROLLUP M: ... M; SCROLLDOWN M: ... M; >XY ( x y -- ) \ Move cursor to x y \ within the window M: ... M; ASTEXT M: ... M; BUILD M: ... M; INHERIT RECT ENDCLASS Figure Eleven. Details derived from LMI demo. HEX METHOD: WAR@ ( addr -- dx cx bx ) \ Fetch parameters for an IBM-PC video 1/0 call DUP >R LOWERRIGHT IN RECT 100 * + \ dx from ul R@ UPPERLEFT IN RECT 100 * + \ cx from lr R> WSIZE 4 * + @ \ bx from the attribute variable METHOD ; METHOD: W-ATTRIB ( attrib addr -- ) \ Change the initializing attribute SWAP 100 * SWAP WSIZE 4 * + ! METHOD; METHOD: W-EXEC ( dx cx bx ax -- ) \ Execute the window function regAX ! regBX ! regCX ! regDX ! 10 INT86 METHOD ; METHOD: W-CLEAR \ Initialize the window WPAR@ 0600 W-EXEC METHOD ; METHOD: W-UP \ Scroll the window up WAR@ 0601 W-EXEC METHOD ; METHOD: W-DOWN \ Scroll the window down WAR@ 0701 W-EXEC METHOD ; (Figurs continues.) January 1992 February 38 Forth Dimensions
pigum Eleoen, continued.) METHOD: W-GOTOXY ( x y addr -- ) \ Cursor addressing within the window UPPERLEFT IN RECT D+ GOTOXY METHOD ; METHOD: W-HOME ( addr -- ) \ Move cursor to the window home position, upper left UPPERLEFT IN RECT GOTOXY METHOD; METHOD: W-LLC ( addr -- ) \ Move the cursor to the lower left corner of window WSIZE + DUP @ SWAP WSIZE + @ GOTOXY METHOD: METHOD: W-BORDER ( addr -- ) \ Draw a border around the window using IBM character set DUP >R UPPERLEFT IN RECT R> LOWERRIGHT IN RECT \ The window parameters are now on the stack OVER 1+ 4 PICK DO \ Do two sides I 3 PICK 1- GOTOXY OC4 EMIT I OVER 1+ GOTOXY OC4 EMIT LOOP DUP 1+ 3 PICK DO \ Do the other sides OVER 1+ I GOTOXY OB3 EMIT 3 PICK 1- I GOTOXY OB3 EMIT LOOP OVER 1+ 3 PICK 1- GOTOXY OBF 3 PICK 1- OVER 1+ GOTOXY OCO 1+ SWAP 1+ SWAP GOTOXY 1- SWAP 1- SWAP GOTOXY METHOD ; DECIMAL community for whom re- usability of code is not important.. .." "Forth has acquired an unfortunate reputation as being highly non-portable, and GB's comments serve to rein- force this impression." ". . .throw away time and effort needed just for a marginal gain in execution speed.. .."His [GB'sl work does not require portability.. ." "No stan- dardis needed who plan to ignore it any- how ..." "... ER and GB's responses add unfortunate confimation to the suspicion that the MI team is writing a new 'Ian to pas Off as "*'" Forth Dimensions ANSI team is dominated by people who do not place much value on portability-and Greg Bailey says as much." These and many similar passages from recent postings of John's serve to create, by repetition, the erroneous impression that members of the TC, includ- ing myself, have little or no interest in portability or reus- ability of code and are doing grievous harm to what John sees as Forth. In fact, this is an erroneous interpretation of at least my position, and I Pmume that the '00' of the problem is that at least until the semantic issue I men- tioned on 16 August is dari- fed, John will continue to EMIT ( urc) EMIT ( llc ) OD9 EMIT ( lrc ) ODA EMIT ( ulc ) misunderstand the motives and actions of the TC. Simply stated, again, my understanding of John Wavrik's position is that to him Forth means (and I pre- sume he believes it was in- tended to mean) a static, open implementation model. For example, he considers that Forth includes a word spelled DOCOL that, when executed, returns a value that can be passed to , (comma) with specific and well-de- fined meaning having to do with the creation of a body of executable code. He also believes that Forth includes words spelled ?BRANCH and OBRANCH that are, and I gather must be, used in implementing control-flow words. He feels likewise about the existence, and likewise about a method of implementation that should be guaranteed to work, for LIT. John, am I misstating your position here at all? I don't think I misunderstand you. What I have heard you say befo~ is that you don't really care what it is, but whatever it turns out to be you want it all (i.e., you really strongly desire a standard that prescribes an implementation-whether you draw the "architectural" boundary there or not-at least completely enough that you know and can manipulate the executable text of a colon definition; that you krww and can manipulate the structure of the dictionary; and so on). My understanding of your position is that a laudable standard could be formed by taking virtually anygood implementation of Forth, documenting the whole thing, and saying that standard Forth must be implemented in this way on all computers. Before I reply in detail to your postings, I think it would be useful to refine with you the above paragraph as needed, so that what we have is a concise but accurate statement of where you draw the line. At the same time, so that we can all calibrate your sensitivity to the performance one may expect of an application written in Forth, I would like to know what you mean by "marginal gains in speed." For example, is a lox performance improvement on a given CPU marginal to you? Readers of these postings might erroneously conceive, for example, that the architecture-independent definition of Forth we have tried to write in the dpANS was undertaken for no other reason than to permit implementations that shave a few percent off execution speed. Nothing could be farther from the truth. I January 1992 February
Page 2 and 3: SILICON COMPOSERS INC Announcing th
Page 4 and 5: Objets dyArt 0 bject-oriented progr
Page 6 and 7: Yerk Comes to the PC Rick Grehan Pe
Page 8 and 9: instance variables can re- solve th
Page 10 and 11: :class. The :class word uses a nest
Page 12 and 13: stance variable names in these alte
Page 14 and 15: ules. (Jim Callahan, Harvard Softwo
Page 16 and 17: Dl77 ( magic seed ) swm 3. Page 24,
Page 18 and 19: y an Engish transla- tion or summar
Page 20 and 21: somewhere, should we just say 'It's
Page 22 and 23: ,Partic@a te! ACM SlGForth '92 Fort
Page 24 and 25: methods is called inbetft- ance. De
Page 26 and 27: the other class's methods. For exam
Page 28 and 29: On-Line Resource Figure Five. The i
Page 30 and 31: of classical Forth.. . And Forth di
Page 32 and 33: (Figure Nine, continued.) : @@ \ (
Page 34 and 35: This partimlar example has been des
Page 36 and 37: (METHODS) DEFINITIONS : ... content
Page 40 and 41: I still feel that we are debating s
Page 42 and 43: indeed, were not particularly encou
Page 44: L Contributions from the Forth Comm

5 - Forth Interest Group

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?