Re: [Ql-Users] RET_STK and debugging SBASIC code
Hi Michael, PICK$ will select the nth item from the list that follows the n. Consider PICK$(n, aaa, bbb, ccc, ddd, etc) If n is 1 then PICK$ will return aaa because it is the 1st item in the list. If n is 5 then etc would be returned because it is the 5th item. The parameters of PICK$ can be of any type: they will be coerced into strings. Expressions can be supplied, for example, dev$ file$. Ah OK, thanks. There is a particular problem that PICK$ may help us to solve. Occasionally, we may want to iterate through a list of items. If these items are strings, then we may well reach for a FOR loop and do something like . . . (...) Which version do you prefer? I'd probably use an array. Thanks though, this looks like an interesting keyword! Wolfgang ___ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
[Ql-Users] RET_STK and debugging SBASIC code
Hi Wolfgang, PICK$ will select the nth item from the list that follows the n. Consider PICK$(n, aaa, bbb, ccc, ddd, etc) If n is 1 then PICK$ will return aaa because it is the 1st item in the list. If n is 5 then etc would be returned because it is the 5th item. The parameters of PICK$ can be of any type: they will be coerced into strings. Expressions can be supplied, for example, dev$ file$. There is a particular problem that PICK$ may help us to solve. Occasionally, we may want to iterate through a list of items. If these items are strings, then we may well reach for a FOR loop and do something like . . . FOR x$ = aaa, bbb, ccc, ddd, etc Unfortunately, this is not allowed. The identifier for a FOR loop has to be numeric, either floating point or integer. This leaves us with a problem: how to do the above? There is a way to do this. A normal numeric FOR loop could be used, and then assign values to x$ depending on the FOR loop index, like this . . . FOR n = 1 TO 5 SELect ON n = 1 : x$ = aaa : = 2 : x$ = bbb : = 3 : x$ = ccc : = 4 : x$ = ddd : = 5 : x$ = etc This can also be done using PICK$ . . . FOR n = 1 TO 5 X$ = PICK$(n, aaa, bbb, ccc, ddd, etc) Which version do you prefer? The version using PICK$ may be more readable, but please bear in mind the following. PICK$ will evaluate all of its parameters before deciding which value to return, so, in terms of efficiency, this would not be the best choice. If outright execution speed is top priority, then the Select version should be chosen. What I like about PICK$ is the readability factor. I use PICK$ in my own programs and can recommend it. Michael ___ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
[Ql-Users] RET_STK and debugging SBASIC code
Hi all, I believe I have discovered a very good way of using the RET_STK function DEFine FuNction bug(p1$, p2$, p3$, p4$, p5$) LOCal n, x$ PRINT #0,PAUSEd at line ! RET_STK ! FOR n = 1 TO 5 x$ = PICK$(n, p1$, p2$, p3$, p4$, p5$) IF PARNAM$(n) OR x$: PRINT #0,!! PARNAM$(n) = x$ ! END FOR n CURSEN #0 : PAUSE : CURDIS #0 PRINT #0, : RETurn 0 END DEFine bug Note that PICK$ is from DIY Toolkit VolE_CONTROL_code. A function is used rather than a procedure so that RET_STK will always produce the correct line number. Suppose I wanted to stop my program under some condition at line 2885 and print out the values of the variables row, col and count. The following line could be inserted 2885 IF some_condition : ERT bug(row,col,count) Then what could appear in #0 is PAUSEd at line 2885 row = 19 col = 20 count = 156 All the parameters are optional. You can even supply expressions, although only their values would get printed. I have found this to be so useful. There is no need to type in any line numbers – RET_STK is doing all the work. Since using this, my debugging has become so much easier and less time-consuming. Michael ___ QL-Users Mailing List http://www.q-v-d.demon.co.uk/smsqe.htm
