Re: Feature Patch: Use completion to view parameter values

[Daniel Shahaf <d.s@daniel.shahaf.name>]

Mikael Magnusson wrote on Tue, Mar 30, 2021 at 07:41:05 +0200:
> On 3/29/21, Daniel Shahaf <d.s@daniel.shahaf.name> wrote:
> > Bart Schaefer wrote on Mon, Mar 29, 2021 at 10:20:08 -0700:
> >> On Mon, Mar 29, 2021 at 10:11 AM Daniel Shahaf <d.s@daniel.shahaf.name>
> >> wrote:
> >> >
> >> > I think that's right.  -workers@: Is it possible for a non-PM_SPECIAL
> >> > parameter have a custom getfn?
> >>
> >> Only with the zsh/param/private module, I think, and in that case the
> >> getfn is just a wrapper around the default and doesn't add any
> >> side-effects.
> >
> > Thanks, Bart.
> >
> > And as to $AUTOINCREMENT, this isn't the first time I mentioned it as
> > a hypothetical, so I'm going to go ahead and post it here.  I suspect
> > people from the future will use this for something-or-other.
> >
> > Works as you'd expect:
> > .
> >     % echo $AUTOINCREMENT $AUTOINCREMENT
> >     0 1
> >     %
> >
> > And in Marlon's patch with the ${(t)…*special*} exclusion bypassed:
> > .
> >     % zstyle \* extra-verbose yes
> >     % AUTOFOO=42
> >     % echo $AUTO<TAB><TAB>
> >     AUTOFOO       -- 42  AUTOINCREMENT -- 2
> >     AUTOFOO       -- 42  AUTOINCREMENT -- 4
> >
> > Yes, it does actually increment the variable twice, probably because the
> > _parameters patch uses both ${(t)${(P)}} and then ${(P)}, and the former
> > does an increment too:
> > .
> >     % echo $AUTOINCREMENT ${(tP)AUTOINCREMENT} $AUTOINCREMENT
> >     0 array-special 2
> >     %
> >
> > I'm not proposing to commit $AUTOINCREMENT.
> >
> > Cheers,
> >
> > Daniel
> >
> > P.S.  Another similar example is Perl's magic flip-flop variable:
> > «perl -E 'say --$| for (1..10)'»
> >
> >
> > diff --git a/Src/Modules/parameter.c b/Src/Modules/parameter.c
> > index ef9148d7b..179ac068e 100644
> > --- a/Src/Modules/parameter.c
> > +++ b/Src/Modules/parameter.c
> > @@ -2136,6 +2136,24 @@ scanpmusergroups(UNUSED(HashTable ht), ScanFunc func,
> > int flags)
> >  }
> >
> >
> > +/* Functions for the AUTOINCREMENT special parameter. */
> > +
> > +static zlong autoincrement = 0;
> > +
> > +static zlong
> > +autoincrementgetfn(UNUSED(Param pm))
> > +{
> > +    return autoincrement++;
> > +}
> > +
> > +static void
> > +autoincrementsetfn(UNUSED(Param pm), zlong value)
> > +{
> > +    autoincrement = value;
> > +}
> 
> If someone hypothetically wanted to use this, this (eg, the static
> zlong autoincrement variable) should either be a zulong, or
> autoincrementgetfn should check for wrapping, otherwise this is
> undefined behavior (hypothetically) (unless we use -fwrapv, but I
> don't think we do).

Thanks, Mikael.  Completely forgot about this.  The signatures in
gsu_integer specify signed and I don't want to deal with signed/unsigned
differences, so:

diff --git a/Src/Modules/parameter.c b/Src/Modules/parameter.c
index 179ac068e..638ccc886 100644
--- a/Src/Modules/parameter.c
+++ b/Src/Modules/parameter.c
@@ -2143,6 +2143,10 @@ static zlong autoincrement = 0;
 static zlong
 autoincrementgetfn(UNUSED(Param pm))
 {
+    if (autoincrement == ZLONG_MAX) {
+	autoincrement = ZLONG_MIN;
+	return ZLONG_MAX;
+    }
     return autoincrement++;
 }
 
diff --git a/Src/zsh.h b/Src/zsh.h
index 6cf1b4186..536d728c5 100644
--- a/Src/zsh.h
+++ b/Src/zsh.h
@@ -38,12 +38,15 @@
 typedef ZSH_64_BIT_TYPE zlong;
 #if defined(ZLONG_IS_LONG_LONG) && defined(LLONG_MAX)
 #define ZLONG_MAX LLONG_MAX
+#define ZLONG_MIN LLONG_MIN
 #else
 #ifdef ZLONG_IS_LONG_64
 #define ZLONG_MAX LONG_MAX
+#define ZLONG_MIN LONG_MIN
 #else
 /* umm... */
 #define  ZLONG_MAX ((zlong)9223372036854775807)
+#define  ZLONG_MIN ((zlong)-9223372036854775808)
 #endif
 #endif
 #ifdef ZSH_64_BIT_UTYPE
@@ -55,6 +58,7 @@ typedef unsigned zlong zulong;
 typedef long zlong;
 typedef unsigned long zulong;
 #define ZLONG_MAX LONG_MAX
+#define ZLONG_MIN LONG_MIN
 #endif
 
 /*
diff --git a/Test/V06parameter.ztst b/Test/V06parameter.ztst
index 27d587852..610422abd 100644
--- a/Test/V06parameter.ztst
+++ b/Test/V06parameter.ztst
@@ -92,6 +92,37 @@
 >foo
 >bar
 
+ repeat 3 echo $AUTOINCREMENT
+ :
+ AUTOINCREMENT=42; 
+ repeat 3 echo $AUTOINCREMENT
+ :
+ AUTOINCREMENT=2147483647
+ repeat 3 echo $AUTOINCREMENT
+ :
+ AUTOINCREMENT=4294967295
+ repeat 3 echo $AUTOINCREMENT
+ :
+ AUTOINCREMENT=9223372036854775807
+ repeat 3 echo $AUTOINCREMENT
+0:$AUTOINCREMENT unit test
+>0
+>1
+>2
+>42
+>43
+>44
+>2147483647
+>2147483648
+>2147483649
+>4294967295
+>4294967296
+>4294967297
+>9223372036854775807
+*>(-9223372036854775808|9223372036854775809)
+*>(-9223372036854775807|9223372036854775810)
+F:This test assumes zlong is at least a 64-bit type.
+
 %clean
 
  rm -f autofn functrace.zsh rocky3.zsh sourcedfile myfunc

Cheers,

Daniel