#!/usr/bin/env bash
# dynamic_scope_demo.sh
# Mirrors the C-like program from the hand-out under dynamic scoping.
 
############################
# global variables (start all at 0)
############################
a=0
b=0
c=0
d=0
 
############################
# g1, g2, g3
############################
g1 () {                 # signature: g1(int b ; int c)
    local b=$1 c=$2
    printf '%d %d %d %d\n' "$a" "$b" "$c" "${d:-0}"
}
 
g2 () {                 # signature: g2(int a ; int c)
    local a=$1 c=$2
    g1 "$a" "$c"
}
 
g3 () {                 # signature: g3(int c ; int a)
    local c=$1 a=$2
 
    local b=3
    g1 "$a" "$b"        # first print-line
 
    # -------- inner block --------
    local c=8           # shadows the parameter c
    local d=4
    g2 "$a" "$b"        # second print-line
    unset d             # end of inner block – restore older ‘d’
    # -------- end block ---------
 
    g1 "$a" "$b"        # third print-line
    echo "$b"           # “return” value
}
 
############################
# main
############################
main () {
    local a=4
    local b=5
    a=$(g3 "$b" "$c")   # c is still the global 0
    g3 "$b" "$a"
}
 
main
 

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