会PHP的人都知道PHP中的print_r/var_export函数，可以方便的用于打印数组或导出变量，Lua中没有提供，实际应用中却是很多时候需要类似的功能。

今天便封装了个简单函数，实现类似功能，用来打印/导出table：

-- dump.lua

--[[
dump对象
@param mixed obj
@return string
]]
function debug.dump(obj)
    local getIndent, quoteStr, wrapKey, wrapVal, dumpObj
    getIndent = function(level)
        return string.rep("\t", level)
    end
    quoteStr = function(str)
        return '"' .. string.gsub(str, '"', '\\"') .. '"'
    end
    wrapKey = function(val)
        if type(val) == "number" then
            return "[" .. val .. "]"
        elseif type(val) == "string" then
            return "[" .. quoteStr(val) .. "]"
        else
            return "[" .. tostring(val) .. "]"
        end
    end
    wrapVal = function(val, level)
        if type(val) == "table" then
            return dumpObj(val, level)
        elseif type(val) == "number" then
            return val
        elseif type(val) == "string" then
            return quoteStr(val)
        else
            return tostring(val)
        end
    end
    dumpObj = function(obj, level)
        if type(obj) ~= "table" then
            return wrapVal(obj)
        end
        level = level + 1
        local tokens = {}
        tokens[#tokens + 1] = "{"
        for k, v in pairs(obj) do
            tokens[#tokens + 1] = getIndent(level) .. wrapKey(k) .. " = " .. wrapVal(v, level) .. ","
        end
        tokens[#tokens + 1] = getIndent(level - 1) .. "}"
        return table.concat(tokens, "\n")
    end
    return dumpObj(obj, 0)
end

测试代码：

-- test.lua

local obj = {
    string = "hello",
    int = 9527,
    float = 3.1415,
    bool = true,
    table = {
        1, 2, 3,
        {
            a = 21,
            b = 22,
            c = 23,
        },
    },
    [88] = 88888,
    [9.7] = 22222,
}
print(debug.dump(obj))

输出结果：

{