shell实现面向对象编程

今天看到一篇博客, 有人实现了 shell 的面向对象功能. 虽然class new 等是用函数实现的, 但是思想非常巧妙, 很有意思, 所以就把它贴在这里, 记录一下.
而且看起来还不是很容易弄明白, 可以打开 set -x 配合源码一起看.

其中使用到了 uuidgen, 依赖于系统中的 uuid-runtime. 如果没有安装, 请安装对应的库, ubuntu中的命令是:

1
apt install uuid-runtime

原文地址: https://coolshell.cn/articles/5035.html

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#!/bin/bash

#---------------------------------
# OO support functions
#---------------------------------
#set -x

DEFCLASS=""
CLASS=""
THIS=0

class() {
    DEFCLASS="$1"
    eval CLASS_${DEFCLASS}_VARS=""
    eval CLASS_${DEFCLASS}_FUNCTIONS=""
}

static() {
    return 0
}

func() {
    local varname="CLASS_${DEFCLASS}_FUNCTIONS"
    eval "$varname=\"\${$varname}$1 \""
}

var() {
    local varname="CLASS_${DEFCLASS}_VARS"
    eval $varname="\"\${$varname}$1 \""
}

loadvar() {
    eval "varlist=\"\$CLASS_${CLASS}_VARS\""
    for var in $varlist; do
        eval "$var=\"\$INSTANCE_${THIS}_$var\""
    done
}

loadfunc() {
    eval "funclist=\"\$CLASS_${CLASS}_FUNCTIONS\""
    for func in $funclist; do
        eval "${func}() { ${CLASS}::${func} \"\$@\"; return \$?; }"
    done
}

savevar() {
    eval "varlist=\"\$CLASS_${CLASS}_VARS\""
    for var in $varlist; do
        eval "INSTANCE_${THIS}_$var=\"\$$var\""
    done
}

typeof() {
    eval echo \$TYPEOF_$1
}

new() {
    local class="$1"
    local cvar="$2"
    shift
    shift
    local id=$(uuidgen | tr A-F a-f | sed -e "s/-//g")
    eval TYPEOF_${id}=$class
    eval $cvar=$id
    local funclist
    eval "funclist=\"\$CLASS_${class}_FUNCTIONS\""
    for func in $funclist; do
        eval "${cvar}.${func}() {
            local t=\$THIS; THIS=$id; local c=\$CLASS; CLASS=$class; loadvar;
            loadfunc; ${class}::${func} \"\$@\"; rt=\$?; savevar; CLASS=\$c;
            THIS=\$t; return $rt;
        }"
    done
    eval "${cvar}.${class} \"\$@\" || true"
}



#---------------------------------------------------
# Example code
#---------------------------------------------------

# class definition
class Storpel
    func Storpel
    func setName
    func setQuality
    func print
    var name
    var quality

# class implementation
Storpel::Storpel() {
    setName "$1"
    setQuality "$2"
    if [ -z "$name" ]; then setName "Generic"; fi
    if [ -z "$quality" ]; then setQuality "Normal"; fi
}

Storpel::setName() { name="$1"; }
Storpel::setQuality() { quality="$1"; }
Storpel::print() { echo "$name ($quality)"; }

#usage
new Storpel one "Storpilator 1000" Medium
new Storpel two
new Storpel three
#
two.setName "Storpilator 2000"
two.setQuality "Strong"

one.print
two.print
three.print

echo ""
echo "one: $one ($(typeof $one))"
echo "two: $two ($(typeof $two))"
echo "Three: $three ($(typeof $three))"