Iterate over $# stored in another variable in another function - sh

Question

How can I iterate over $# after it has been stored in another variable in another function?
Note this is about the sh shell, not bash.
My code (super simplified):
#! /bin/sh
set -- a b "c d"
args=
argv() {
shift # pretend handling options
args="$#" # remaining arguments
}
fun() {
for arg in "$args"; do
echo "+$arg+"
done
}
argv "$#"
fun
Output:
+b c d+
I want:
+b+
+c d+
The special variable $# stores argv preserving whitespace. The for loop can loop over $# also preserving whitespace.
set -- a b "c d"
for arg in "$#"; do
echo "+$arg+"
done
Output:
+a+
+b+
+c d+
But once $# is assigned to another variable the whitespace preserving is gone.
set -- a b "c d"
args="$#"
for arg in "$args"; do
echo "+$arg+"
done
Output
+a b c d+
Without quotes:
for arg in $args; do
echo "+$arg+"
done
Output:
+a+
+b+
+c+
+d+
In bash it can be done using arrays.
set -- a b "c d"
args=("$#")
for arg in "${args[#]}"; do
echo "+$arg+"
done
Output:
+a+
+b+
+c d+
Can that be done in the sh shell?

Answer 1

You could use shift again inside fun if you know the shift has been performed in argv.
#! /bin/sh
set -- a b "c d"
args=
argv() {
shifted=1 # pretend handling options
shift $shifted
}
fun() {
[ -n $shifted ] && shift $shifted
for arg; do
echo "+$arg+"
done
}
argv "$#"
fun "$#"
Output:
+b+
+c d+

Answer 2

Here are two workarounds. Both have caveats.
First workaround: put newlines between arguments then use read.
set -- a b " c d "
args=
argv() {
shift
for arg in "$#"; do
args="$args$arg\n"
done
}
fun() {
printf "$args" | while IFS= read -r arg; do
echo "+$arg+"
done
}
argv "$#"
fun
Output:
+b+
+ c d +
Note that even the spaces before and after are preserved.
Caveat: if the arguments contain newlines you are screwed.
Second workaround: put quotes around arguments then use eval.
set -- a b " c d "
args=
argv() {
shift
for arg in "$#"; do
args="$args \"$arg\""
done
}
fun() {
for arg in "$#"; do
echo "+$arg+"
done
}
argv "$#"
eval fun "$args"
Caveat: if the arguments contain quotes you are screwed.