On Thu, Jan 24, 2013 at 10:05 PM, David Korn <[email protected]> wrote:
> cc: [email protected]
> Subject: Re: [ast-users] nameref confusion--not expanding as expected?
> --------
>
> This is caused by a for loop optimizer bug. It treated $v as a loop
> invariant. I am looking for a solution.
I'm not sure whether it's a bug at all... the issue is that he uses
"nameref v" to declare a nameref but doesn't give the nameref a
variable name as input. Technically the first assignment of a value to
a nameref defines the name of the variable it will access while
following accesses set the value of the alias'ed variable.
Changing Aaron's example to this version fixes the problems:
-- snip --
set -e
set -u
print ${.sh.version}
function dumpParams # array
{
set -eu
nameref a=$1
shift
nameref v
print '--- works'
for v in "${a[@]}"
do
print "${!v}=$v"
done
print '---'
}
function dumpParams2 # array
{
set -eu
nameref a=$1
shift
print '--- doesn'\''t work'
for vn in "${a[@]}"
do
nameref v=$vn
print "${!v}" = "$v"
done
print '---'
}
foo=1
bar=2
baz=3
array=(foo bar baz)
dumpParams array
print
dumpParams2 array
-- snip --
Unified diff looks like this:
-- snip --
--- aaron_nameref_original.sh 2013-01-24 22:32:28.122995107 +0100
+++ aaron_nameref_working.sh 2013-01-24 22:32:14.169997998 +0100
@@ -22,10 +22,11 @@
set -eu
nameref a=$1
shift
- nameref v
+
print '--- doesn'\''t work'
- for v in "${a[@]}"
+ for vn in "${a[@]}"
do
+ nameref v=$vn
print "${!v}" = "$v"
done
print '---'
-- snip --
The fix is simply to re-declare the nameref each time it should alias
a new variable (or array element).
----
Bye,
Roland
--
__ . . __
(o.\ \/ /.o) [email protected]
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