* Re: "Array" variables that aren't set, and NO_UNSET
1996-07-22 19:35 "Array" variables that aren't set, and NO_UNSET Bart Schaefer
@ 1996-07-23 12:17 ` Peter Stephenson
0 siblings, 0 replies; 2+ messages in thread
From: Peter Stephenson @ 1996-07-23 12:17 UTC (permalink / raw)
To: Zsh hackers list
schaefer@candle.brasslantern.com wrote:
> Consider:
>
> zsh% setopt | grep set
> nounset off
> zsh% echo ${thisisnotavariable}
>
> zsh% echo ${thisisnotavariable[1]}
> zsh: closing brace expected
> zsh%
>
> Why is it a *syntax* error to subscript a variable that's not set, when
> it is not a syntax error to refer to the string value of such a variable?
This does seem inconsistent. The problem is that getvalue() doesn't
bother parsing any further if it finds the variable is unset.
This patch is one suggestion, though I suspect there may be others.
Parsing continues (that's the first hunk), and one then has to be
careful that the parameter struct v->pm is not dereferenced since it
may now be null (that's all the rest). The change to check this in
getstrvalue() is necessary; the changes in getintvalue() and
getarrvalue() shouldn't be if everything is going according to plan,
but I have made them anyway.
It's very intricate, so it's rather hard to be completely certain
v->pm won't get dereferenced. Perhaps there's a better way of doing
it. Make v->pm instead reference a dummy scalar? That's hard too,
since if getvalue() returns non-zero then v->pm is liable to be
hijacked and altered. I'm not sure there's currently any way of making
readonlyness watertight.
*** Src/params.c~ Mon Jul 1 19:10:53 1996
--- Src/params.c Tue Jul 23 13:49:28 1996
***************
*** 549,560 ****
if (sav)
*s = sav;
*pptr = s;
- if (!pm || (pm->flags & PM_UNSET))
- return NULL;
v = (Value) hcalloc(sizeof *v);
! if (PM_TYPE(pm->flags) == PM_ARRAY)
v->isarr = isvarat ? -1 : 1;
! v->pm = pm;
v->inv = 0;
v->a = 0;
v->b = -1;
--- 549,558 ----
if (sav)
*s = sav;
*pptr = s;
v = (Value) hcalloc(sizeof *v);
! if (pm && PM_TYPE(pm->flags) == PM_ARRAY)
v->isarr = isvarat ? -1 : 1;
! v->pm = (pm && !(pm->flags & PM_UNSET)) ? pm : NULL;
v->inv = 0;
v->a = 0;
v->b = -1;
***************
*** 602,608 ****
while (*s != ']' && *s != Outbrack)
s++;
*pptr = s;
! return v;
}
} else {
if (a > 0)
--- 600,606 ----
while (*s != ']' && *s != Outbrack)
s++;
*pptr = s;
! return v->pm ? v : NULL;
}
} else {
if (a > 0)
***************
*** 642,648 ****
zerr("subscript to %s: %d", (v->b < 0) ? "small" : "big", v->b);
return NULL;
}
! return v;
}
/**/
--- 640,646 ----
zerr("subscript to %s: %d", (v->b < 0) ? "small" : "big", v->b);
return NULL;
}
! return v->pm ? v : NULL;
}
/**/
***************
*** 652,658 ****
char *s, **ss;
static char buf[(SIZEOF_LONG * 8) + 4];
! if (!v)
return "";
if (v->inv) {
sprintf(buf, "%d", v->a);
--- 650,656 ----
char *s, **ss;
static char buf[(SIZEOF_LONG * 8) + 4];
! if (!v || !v->pm)
return "";
if (v->inv) {
sprintf(buf, "%d", v->a);
***************
*** 704,710 ****
{
char **s;
! if (!v)
return arrdup(nular);
if (v->inv) {
char buf[DIGBUFSIZE];
--- 702,708 ----
{
char **s;
! if (!v || !v->pm)
return arrdup(nular);
if (v->inv) {
char buf[DIGBUFSIZE];
***************
*** 736,742 ****
long
getintvalue(Value v)
{
! if (!v || v->isarr)
return 0;
if (v->inv)
return v->a;
--- 734,740 ----
long
getintvalue(Value v)
{
! if (!v || !v->pm || v->isarr)
return 0;
if (v->inv)
return v->a;
--
Peter Stephenson <pws@ifh.de> Tel: +49 33762 77366
WWW: http://www.ifh.de/~pws/ Fax: +49 33762 77330
Deutches Electronen-Synchrotron --- Institut fuer Hochenergiephysik Zeuthen
DESY-IfH, 15735 Zeuthen, Germany.
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