无需在 LUA 中创建变量即可从函数中获取多个值 [英] Getting multiple values from a function without creating a variables in LUA

问题描述

有没有办法从一个函数中获取多个值而不为它创建变量?

Is there any way to get several values from a function without creating variables for it?

local major, minor, revision, codename = love.getVersion() -- Get current LÖVE version as a string.

因此，我们将使用一些只会返回您需要的值的东西，而不是创建四个不同的变量(或数组).

So instead of making four different variables (or array) we'll use something that will just return a value you need.

get( love.getVersion(), 0 ) -- Will return the first value (major).

我在某处读到我可以使用方括号并尝试了love.getVersion()[1]，但它说尝试索引一个数值."

I read somewhere that I can use square brackets and triedlove.getVersion()[1] but it says "Attempt to index a number value."

推荐答案

为了举例，我们假设 love.getVersion() 定义如下:

For the sake of example let's assume that love.getVersion() is defined as follows:

function love.getVersion ()
   return 1, 2, 3, "four"
end

使用select(index, ...):

如果index 是数字，则select 返回index 的参数索引之后的所有参数.考虑:

Using select(index, ...):

If index is number then select returns all arguments after argument index of index. Consider:

print("A:", select(3, love.getVersion()))
local revision = select(3, love.getVersion())
print("B:", revision)

输出:

A:  3   four
B:  3

如有疑问 - 参考手册 - select.

In case of doubts - Reference Manual - select.

您提到尝试 love.getVersion()[0].这就是差不多，但您首先需要将返回的值包装到一个实际的表中:

You have mentioned trying love.getVersion()[0]. That's almost it, but you first need to wrap the values returned into an actual table:

local all_of_them = {love.getVersion()}
print("C:", all_of_them[4])

输出:

C:  four

如果您想在一行中完成(本着不创建变量"的精神)，您还需要将表格括在括号中:

In case you want to do it in one line (in the spirit of "without creating a variables") you need to wrap the table in parentheses, too:

print("D:", ({love.getVersion()})[1])

输出:

D:  1

使用 _ 变量:

来自其他语言，您可以使用 _ 分配您不感兴趣的值(如果它是一条短平线，没有人会注意到我们创建了一个变量)，如:

Using the _ variable:

Coming from the other languages you can just assign values you are not interested in with _ (nobody will notice we create a variable if it is a short flat line), as in:

local _, minor = love.getVersion()
print("E:", minor)

输出:

E:  2

请注意，我在示例中跳过了以下任何_(不需要local _, minor, _, _).

Please note that I skipped any following _ in the example (no need for local _, minor, _, _).

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