% cat s
puts(){ 
  printf 'the shell splits my args like this: \n'
  printf '\t\t%s\n' "$@"
  }
  
s=a:b:c ifs=$IFS IFS=: # save the current IFS and change it

puts $s

IFS=$ifs # restore default IFS  

puts $s

% sh s
the shell splits my args like this: 
                a
                b
                c
the shell splits my args like this: 
                a:b:c

% cat s
puts(){ 
  printf 'the shell splits my args like this: \n'
  printf '\t\t%s\n' "$@"
  }

s=a:b:c
  
( 
  IFS=: # inside a sub-shell because of the () 
  echo now inside ...
  puts $s

)

echo now outiside ...

puts $s

% ash s
now inside ...
the shell splits my args like this: 
                a
                b
                c
now outiside ...
the shell splits my args like this: 
                a:b:c

echo "$var"

printf '%s\n' "$var"

echo $var