如何在Lua中的函数内调用函数？

Question

I have this code:

function test()
    function awesome()
        print("im awesome!")
    end

    function notawesome()
        print("im not awesome.")
    end

    function notevenawesome()
        print("im not even awesome...")
    end
end

test().notawesome()

When I run this, the console prints

15: attempt to index a nil value

What I'm trying to do is call the function notawesome() within the function test() , how would I do that?

Answer 1

Your function is not returning anything (thus returning nil). Something like this should work:

function test()
    function awesome()
        print("im awesome!")
    end

    function notawesome()
        print("im not awesome.")
    end

    function notevenawesome()
        print("im not even awesome...")
    end
    result = {}
    result["notawesome"] = notawesome
    result["awesome"] = awesome
    result["notevenawesome"] = notevenawesome
    return result
end
test().notawesome()

Answer 2

@Axnyff explains what you might be trying to do. I'll explain what you did.

If you are familiar with other languages, please note that Lua does not have function declarations ; It has function definitions , which are expressions that produce a function value when evaluated. Function definition statements, which you have used, are just shortcuts that implicitly include an assignment. See the manual.

When you run your code, a function definition is evaluated and the resulting function value is assigned to the variable test . Then the variable test is evaluated and its value is called as a function (and it is one).

When that function executes, three function definitions are evaluated and assigned to the variables awesome , notawesome , and notevenawesome , repsectively. It doesn't return anything.

So, when the result of calling test ( nil ) is indexed by the string "awesome", you get the error.

If you wanted to call the function value referred by the variable awesome , just do awesome() .

Answer 3

If you want to achieve that instead to use the main function you can use an object:

test = {
    awesome = (function()
        return 'im awesome!'
    end),
    notawesome = (function()
        return 'im not awesome.'
    end),
    notevenawesome = (function()
        return 'im not even awesome...'
    end)
}

To call your functions use this:

print(test.notawesome())    --> im not awesome.