无法使用Lua导入模块，导致尝试索引全局“测试"(nil值) [英] Cannot import module with Lua, results in attempt to index global 'test' (a nil value)

问题描述

没有成功，我尝试使用require关键字将自己的Lua文件导入其他脚本，但是每当我尝试调用导入模块中包含的任何函数(例如"test.lua")时，我都会遇到随后的错误:

Without success I have attempted to import my own Lua files into other scripts using the require keyword but whenever I attempt to call any functions contained within the imported module (e.g. "test.lua") I reach the subsequent error:

require 'test'
test.method(args)
==> yields error: 
==> Attempt to index global 'test' (a nil value) 

我已经将文件添加到package.path中，以防出现问题，但是再次没有开始错误，表明它无法在Lua的路径中找到该文件.

I've added the file to the package.path in case this was the issue, but again there was no beginning error indicating that it cannot find the file in Lua's pathway.

package.path = package.path .. ";/path/to/test.lua"
require 'test'
test.method(args)
==> yields error: 
==> Attempt to index global 'test' (a nil value) 

我正在从文件所在的目录运行交互式Lua Shell.尝试打印局部变量名称时，例如本地测试=要求测试"值为零.

I'm running an interactive Lua shell from the directory where the file is. When attempting to print the local variable name, e.g. local test = require "test" the value is nil.

package.path = package.path .. ";/path/to/test.lua"
local test = require 'test'
print(test)
==> nil

有什么想法吗? (注意:一般来说，我也需要文件而不将其分配给局部变量，并再次使用nil作为返回值打印其值.)

Thoughts? (Note: I also required the file in general without assigning it to a local variable and printed its values again with nil as the returned value.)

推荐答案

扩展lhf的答案:

Lua shell一次读取一个语句.然后，它使用loadstring函数(或更准确的说是C API等效函数)加载代码字符串，该函数编译Lua代码并返回执行该代码的函数.由于每个语句分别加载，并且产生不同的功能，因此它们不共享局部变量.

The Lua shell reads one statement at a time. It then loads the code string with the loadstring function (or more accurately, the C API equivalent), which compiles the Lua code and returns a function that executes it. Since each statement is loaded separately, and produces a different function, they don't share local variables.

本质上，此控制台输入:

Essentially, this console input:

local test = require "test"

print(test)

if test then
    bar()
end

已翻译为:

(function() local test = require "test" end)()

(function() print(test) end)()

(function()
    if test then
        bar()
    end
end)()

(请注意，这也适用于文件.Lua'files'实际上只是具有隐式function(...)签名的函数.这意味着您可以从文件的顶层返回，也可以执行您所执行的任何操作也可以处理文件上的功能(沙盒等).

(Note that this applies to files as well. Lua 'files' are actually just functions with an implicit function(...) signature. This means you can return from the top-level of a file, as well as perform any operations you can do on functions (sandboxing, etc) on files as well.)

如果您要从某处复制代码，则可以将代码包围在do ... end中，如下所示:

If you're copying code from somewhere, you can surround the code in do ... end, like so:

do
    local test = require "test"
    print(test)
end

do ... end块被视为一条语句，并且作用域局部变量.

The do ... end block counts as one statement, and scopes local variables.

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