Re: Converting Files

[ROBERT HOLMGREN]

Robert:

 PMJI, but I've been thinking about your problem with superfluous MoDe
statements. Even when they don't get in the way of work, they're offensive.
Messy theory and messy practice: a muddle. This BBS has posted XyQuest
documents strewn with them; it always made me wonder. Anyway... I see some
difficulties with Sysop's contention that "a program could be easily written to
strip out superfluous MODE commands". Strikes me as not easy! On the one
hand, if you limit yourself to III+ two-character MDNM, MDIT, MDRV, etc
statements, you can do CIA's from TopFile and it's a piece of cake; the schema
you describe (kill the first of two adjacent MoDe commands) suffices. But
simplicity ends there. Consider some of the values on my system, as an
example:
      Sig|Xy4 evaluate this as !
      Sig|Xy4 evaluate this as !
    All equivalent
-More-   Now what?
   Ho ho!
 In short, you require a wee bit of programming. I've been thinking about how
to approach it, and what tools to use, in idle moments. Here's a stab at the
problem. I begin with some dumb CIAs from TOF to wipe out the easy stuff --
i.e., 75% of your problem. With the remaining MoDe statements, I begin at EOF
(this could be more sophisticated, but it's a broad-brush attempt to get
something that works, so it attacks whole files only). I examine the value of
 after each MoDe statement (to figure out what mode we're in), and then
convert that value (if a $tring like BO or BR) into a number using  and
the like (if we're already in a numeric MoDe like , this step is
unnecessary). I then compare the numeric result to the numeric MoDe value
which pertained immediately *before* this MoDe statement. If they're
identical, the second statement gets zapped. This works for an awful lot of
it. It isn't perfect, though -- largely because Xy isn't perfect (not that I
claim perfection either, but...). And, as a matter of taste, you might prefer
different results in some cases. For example, if you take the sample
statements above, and run my PM against them, you get:

 
 
 
 
-More- 

 First, note that because two equivalent simple MD statements were contiguous
(), the former of the two got zapped. You might prefer to have MDUL
instead of MD9, but on the host Xy4 installation (mine), they're identical, so
its no error. Second, note the absurdity of retaining  after  has
wiped out any possibility that MDIT might be hanging around. But Xy generates
different  numeric values before and after the , so what can I
say?

 Note that the PM ain't the fastest, & it *looks* awful whilst running, but
you'd better leave the screen on (don't DX), because recurrent
JMPs|DeFines&Rubouts|CPs tend to get all messed up (Sig and Xy4 have gotten
worse and worse in this respect). Better to do something else (true preemptive
protected multitasking OS/2!). May work under NB too (remove the
">0>..." statement but retain "" right after ). No
exhaustive testing! No warranty! Ciao

*Enclosed File: STRIPMD.PM