Lua - Local variable scope in function

Question

I have the following function

function test()

  local function test2()
      print(a)
  end
  local a = 1
  test2()
end

test()

This prints out nil

The following script

local a = 1
function test()

    local function test2()
        print(a)
    end

    test2()
end

test()

prints out 1.

I do not understand this. I thought declaring a local variable makes it valid in its entire block. Since the variable 'a' is declared in the test()-function scope, and the test2()-function is declared in the same scope, why does not test2() have access to test() local variable?

Answer 1

test2 has has access to variables which have already been declared. Order matters. So, declare a before test2:

function test()

    local a; -- same scope, declared first

    local function test2()
        print(a);
    end

    a = 1;

    test2(); -- prints 1

end

test();

Answer 2

You get nil in the first example because no declaration for a has been seen when a is used and so the compiler declares a to be a global. Setting a right before calling test will work. But it won't if you declare a as local.