title: Error when attempting to call function in different lua file (function is a nil value)
body: <p>I get the following error when I attempt to use call a function in a box collider object I'm trying to make. </p>
  
  <p>The Error:</p>
  
  <p>main.lua:26: attempt to call field 'Update' ( a nil value )</p>
  
  <p>Traceback</p>
  
  <p>main.lua:26: in function 'update'
  [C]: in function 'xpcall'</p>
  
  <p>The Code:</p>
  
  <h2>main.lua</h2>
  
  
  
  <pre class="lang-lua prettyprint-override"><code>require("BoxCollider")
  
  local s1 = {}
  s1.x = 10
  s1.y = 10
  s1.w = 10
  s1.h = 10
  s1.collider = BoxCollider.new(s1.x,s1.y,s1.w,s1.h)
  
  test = BoxCollider.new(40, 7,15,15)
  
  function love.load()
  
  end
  
  function love.update(dt)
  
  if love.keyboard.isDown("d") then s1.x = s1.x + 100 * dt end    
  ---[[   
  s1.collider:Update(s1.x,s1.y)
  
  if s1.collider:CheckCollisions(test) then
      s1.x = 10
  end
  --]]
  end
  
  function love.draw()
  
  love.graphics.rectangle("fill", s1.x, s1.y, s1.w, s1.h)
  love.graphics.rectangle("fill", 40, 7, 15,15)
  
  end
  </code></pre>
  
  <h2>BoxCollider.lua</h2>
  
  <pre class="lang-lua prettyprint-override"><code>BoxCollider = {}
  BoxCollider._index = BoxCollider
  
  
  --x is the x point of the collider, should be equal to the object's x point if the box        is for an object
  --y is the y point of the collider, should be equal to the object's x point if the box is for an object
  --w is the width of the box
  --h is the height of the box
  
  function BoxCollider.new(x,y,w,h)
  return setmetatable({x = x or 0, y = y or 0, w = w or 0, h = h or 0},BoxCollider)
  end
  
  function BoxCollider:CheckCollisions( v )
  
  return self.x &lt; (v.x + v.h) and  v.x &lt; (self.x + self.w) and self.y  &lt; (v.y+v.h) and v.y &lt; (self.y+self.h)  
  
  end
  
  function BoxCollider:reSize(nw,nh)
  self.w = nw
  self.h = nh
  
  end
  
  function BoxCollider:Update(nx,ny)
  self.x = nx
  self.y = ny
  end
  </code></pre>