Bash stack implementation

#!/usr/bin/env bash

# stack constructor: stack name [ value ]*
#
# This creates a global stack object and a collection of functions of the form
# name.method which are defined below.
#
# Example:
#
# $ source split_stack
# $ stack name
# $ name.push 20 30 40
# $ echo $( name.dump )
# 20 30 40
# $ echo $( name.tos )
# 40
# $ name.pop
# $ echo $( name.dump )
# 20 30
#
# This type of use is also valid:
#
# $ object=name
# $ $object.push 50
# $ echo $( $object.dump )
# 20 30 50

function stack( ) {
    local name=$1
    shift
    unset stack_$name
    declare -a -g stack_$name
    object_create "$name" "_stack_"
    $name.push "$@"
}

# name.forget
#
# Destroys the named stack

function _stack_forget( ) {
    local name=$1
    unset stack_$name
    object_destroy "$name"
}

# name.copy new
#
# Creates a copy of the named stack as new

function _stack_copy( ) {
    local name=$1
    local new_name=$2
    stack "$new_name"
    $new_name.push $( $name.dump )
}

# name.push [ value ]*
#
# Pushes values to the stack.

function _stack_push( ) {
    local -n stack=stack_$1
    shift
    while (( $# > 0 ))
    do
        local value=$1
        local count=${#stack[@]}
        stack[$count]=$value
        shift
    done
}

# name.tos
#
# Outputs the current top of stack

function _stack_tos( ) {
    local -n stack=stack_$1
    local count=${#stack[@]}
    let index="count - 1"
    (( index < 0 )) && return 1
    echo "${stack[$index]}"
}

# name.pop
#
# Removes the current top of stack

function _stack_pop( ) {
    local -n stack=stack_$1
    local count=${#stack[@]}
    let index="count - 1"
    (( index < 0 )) && return 1
    unset stack[$index]
}

# name.depth
#
# Outputs the number of items on the stack

function _stack_depth( ) {
    local -n stack=stack_$1
    echo ${#stack[@]}
}

# name.dump
#
# Convenience function to output the contents of the stack

function _stack_dump( ) {
    local -n stack=stack_$1
    for value in "${stack[@]}"
    do
        echo "$value"
    done
}

# Object functions

# object_create name pattern

function object_create( ) {
    local name=$1
    local pattern=$2
    local methods=$( declare -F | grep " $pattern" | sed "s/^declare -f $pattern//" )
    for method in ${methods[@]}
    do
        method_create "$name.$method" "$pattern$method" "$name"
    done
}

# object_destroy name

function object_destroy( ) {
    local name=$1
    local methods=$( declare -F | grep " $name\." | sed "s/^declare -f //" )
    for method in ${methods[@]}
    do
        unset -f "$method"
    done
}

# method_create name function args ...

function method_create( ) {
    local name=$1
    shift
    eval "$name( ) { "$@" \"\$@\" ; }"
}