Math assignment to arrays: Is this a bug?

Math assignment to arrays: Is this a bug?

[Bart Schaefer]

Try this but be prepared to interrupt it:

x=()
for (( x=1; x <= 10; x++ )) print $x

An infinite stream of "1" is the output.

Put "unset x" between the two lines of the example and it works fine.

Change the example to

x=()
for (( x=1; x <= 10; x++ )) typeset x

and you get an infinite stream of "x=(1)".

Why doesn't the assignment of 1 to x in the loop reset it from array to
scalar?

Re: Math assignment to arrays: Is this a bug?

[Peter Stephenson]

Bart Schaefer <schaefer@brasslantern.com> wrote:
> Try this but be prepared to interrupt it:
> 
> x=()
> for (( x=1; x <= 10; x++ )) print $x
> 
> Why doesn't the assignment of 1 to x in the loop reset it from array to
> scalar?

This is inconsistent with normal assignment, so it probably needs fixing.
I've copied the corresponding code from assignsparam(), which has an
unset(KSHARRAYS) test there: not sure what that's doing.  setiparam() is
almost a duplicate of setnparam(); it's not worth having it separate.

Index: Src/params.c
===================================================================
RCS file: /cvsroot/zsh/zsh/Src/params.c,v
retrieving revision 1.119
diff -u -r1.119 params.c
--- Src/params.c	10 Sep 2006 18:10:49 -0000	1.119
+++ Src/params.c	11 Sep 2006 10:56:46 -0000
@@ -2495,46 +2495,9 @@
     return v->pm;
 }
 
-/**/
-mod_export Param
-setiparam(char *s, zlong val)
-{
-    struct value vbuf;
-    Value v;
-    char *t = s, *ss;
-    Param pm;
-    mnumber mnval;
-
-    if (!isident(s)) {
-	zerr("not an identifier: %s", s);
-	errflag = 1;
-	return NULL;
-    }
-    queue_signals();
-    if (!(v = getvalue(&vbuf, &s, 1))) {
-	if ((ss = strchr(s, '[')))
-	    *ss = '\0';
-	if (!(pm = createparam(t, ss ? PM_ARRAY : PM_INTEGER)))
-	    pm = (Param) paramtab->getnode(paramtab, t);
-	DPUTS(!pm, "BUG: parameter not created");
-	if (ss) {
-	    *ss = '[';
-	} else {
-	    pm->base = outputradix;
-	}
-	v = getvalue(&vbuf, &t, 1);
-	DPUTS(!v, "BUG: value not found for new parameter");
-    }
-    mnval.type = MN_INTEGER;
-    mnval.u.l = val;
-    setnumvalue(v, mnval);
-    unqueue_signals();
-    return v->pm;
-}
 
 /*
- * Like setiparam(), but can take an mnumber which can be integer or
- * floating.
+ * Set a generic shell number, floating point or integer.
  */
 
 /**/
@@ -2543,7 +2506,7 @@
 {
     struct value vbuf;
     Value v;
-    char *t = s, *ss = NULL;
+    char *t = s, *ss;
     Param pm;
 
     if (!isident(s)) {
@@ -2552,8 +2515,23 @@
 	return NULL;
     }
     queue_signals();
-    if (!(v = getvalue(&vbuf, &s, 1))) {
-	if ((ss = strchr(s, '[')))
+    ss = strchr(s, '[');
+    v = getvalue(&vbuf, &s, 1);
+    if (v && (v->pm->node.flags & (PM_ARRAY|PM_HASHED)) &&
+	!(v->pm->node.flags & (PM_SPECIAL|PM_TIED)) &&
+	/*
+	 * not sure what KSHARRAYS has got to do with this...
+	 * copied this from assignsparam().
+	 */
+	unset(KSHARRAYS) && !ss) {
+	unsetparam_pm(v->pm, 0, 1);
+	s = t;
+	v = NULL;
+    }
+    if (!v) {
+	/* s has been updated by getvalue, so check again */
+	ss = strchr(s, '[');
+	if (ss)
 	    *ss = '\0';
 	pm = createparam(t, ss ? PM_ARRAY :
 			 (val.type & MN_INTEGER) ? PM_INTEGER : PM_FFLOAT);
@@ -2573,6 +2551,19 @@
     return v->pm;
 }
 
+/* Simplified interface to setnparam */
+
+/**/
+mod_export Param
+setiparam(char *s, zlong val)
+{
+    mnumber mnval;
+    mnval.type = MN_INTEGER;
+    mnval.u.l = val;
+    return setnparam(s, mnval);
+}
+
+
 /* Unset a parameter */
 
 /**/
Index: Test/C01arith.ztst
===================================================================
RCS file: /cvsroot/zsh/zsh/Test/C01arith.ztst,v
retrieving revision 1.9
diff -u -r1.9 C01arith.ztst
--- Test/C01arith.ztst	30 Nov 2004 14:14:57 -0000	1.9
+++ Test/C01arith.ztst	11 Sep 2006 10:56:46 -0000
@@ -97,6 +97,12 @@
 0:setting array elements in math context
 >array 1 2
 
+  xarr=()
+  (( xarr = 3 ))
+  print ${(t)xarr} $xarr
+0:converting type from array
+>integer 3
+
   print $(( 13 = 42 ))
 1:bad lvalue
 ?(eval):1: lvalue required


-- 
Peter Stephenson <pws@csr.com>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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