NextFile

This routine gets the next file out of a directory, without tying the rest of your program into the directory processing loop.

The demo part of the program below is just to demonstrate how the routine can follow more than one thread in parallel. (Of course, the GLObal variables dirpos and dirlen could simply be added as parameters to the two main routines instead.)

The NextFile presented here is merely a skeleton that can be the basis for many different needs. For example one could add conditions for only returning the names of files with certain extensions - or other criteria. The same goes for the information returned: Perhaps the file length is wanted, or the type, etc.

This version also does not drill down into sub directories. That requires a somewhat different design. (I used a GLObal stack for the channel numbers.. See DelDir for one way of doing something like that.)

SuperBASIC users will have to alter the r.xx variables. (I use these as a convention to indicate that these are merely return parameters.) Note also that the directories used in this demo dont exist, so youll have to alter the code to point to some real directories or fake ram1_d1_ and ram1_d2_ to test.

10 cw0 = 0: cw1 = 1: cw2 = 2: FOR c = 0 TO 2: CLS#c
11 :
12 ch1 = Init('ram1_d1_', dl1, dp1): ERT ch1
13 ch2 = Init('ram1_d2_', dl2, dp2)
14 IF ch2 < 0: CLOSE#ch1: ERT ch2
15 :
16 er1 = 0: er2 = 0
17 REPeat lp
18  IF er1 AND er2: EXIT lp
19  IF NOT er1 THEN
20   er1 = NextThread(ch1, dl1, dp1)
21   IF NOT er1 THEN
22    PRINT#cw1; fnm$\, DATE$(dt)
23   ELSE
24    PRINT#cw0; 'Thread 1'! er1
25   END IF
26  END IF
27 :
28  IF NOT er2 THEN
29   er2 = NextThread(ch2, dl2, dp2)
30   IF NOT er2 THEN
31    PRINT#cw2; fnm$\, DATE$(dt)
32   ELSE
33    PRINT#cw0; 'Thread 2'! er2
34   END IF
35  END IF
36 END REPeat lp
37 :
38 DEFine FuNction Init(dir$, dirlen, dirpos)
39 rem Updates parameters dirlen and dirpos
40 RETurn DirInit(dir$)
41 END DEFine Init
42 :
43 DEFine FuNction NextThread(ch, dirlen, dirpos)
44 rem GLObal fnm$, dt
45 rem Updates parameter dirpos
46 RETurn NextFile(ch, fnm$, dt)
47 END DEFine NextThread
48 :
49 :
100 REMark + ------------------------------------------------------------------------ +
101 REMark |<                               Next File                                >|
102 REMark + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +
103 REMark | Get the next file in a directory.                                        |
104 REMark | The routine must have been initiated by DirInit first. It is possible    |
105 REMark | to have more than one "process" using the utility at the same time,      |
106 REMark | provided each process maintains it own LOCal channel, and dirpos &       |
107 REMark | dirlen variables.                                                        |
108 REMark + ------------------------------------------------------------------------ +
109 REMark | V0.01, pjw, 1gg5                                                         |
110 REMark | V0.10, pjw, November 16th 2017, one level only                           |
111 REMark | V0.11, pjw, 2021 Oct 04, tweak                                           |
112 REMark + ------------------------------------------------------------------------ +
113 :
114 DEFine FuNction NextFile(ch, r.nm$, r.dt)
115 LOCal lp, t%
116 REMark GLObal dirlen, dirpos
117 :
118 REPeat lp
119  dirpos = dirpos + 64: IF dirpos >= dirlen: CLOSE#ch: RETurn -10
120  BGET#ch\ dirpos + 5, t%
121  IF t% = 255: NEXT lp
122  GET#ch\ dirpos + 14, r.nm$
123  IF LEN(r.nm$) > 0: EXIT lp
124 END REPeat lp
125 LGET#ch\ dirpos + 52, r.dt
126 RETurn 0
127 END DEFine NextFile
128 :
129 DEFine FuNction DirInit(dir$)
130 LOCal ch
131 REMark GLObal dirlen, dirpos
132 :
133 ch = FOP_DIR(dir$): IF ch < 0: RETurn ch
134 dirlen = FLEN(#ch): dirpos = -64
135 RETurn ch
136 END DEFine DirInit
137 :
138 :

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