Lua – Corona SDK – Calling an instance or class method from EventListener

--in foo.lua 
Foo = {}

--constructor
function Foo:new(x, y)
 --the new instance
 local foo = display. newImage("foo.png")
 - set some instance vars
 foo.x = x
 foo.y = y
 foo.name ='foo' 

 --instance method
 function foo:speak()
 print("I am an instance and my name is ".. self.name)
 end
 
 --another instance method 
 function foo:moveLeft()
 self.x = self.x-1
 end

 function foo:drag( event)
 self.x = event.x
 self.y = event.y 
 end

 foo:addEventListener("touch", drag)

 return foo
end

--class method
function Foo:speak()
 print("I am the class Foo")
end

return Foo

function foo:touch(event)
 self.x = event.x
 self.y = event. y 
end

foo:addEventListener("touch", foo)

player.touch = player.drag

I have a Foo class (well, a pseudo-class) set up as follows:

--in foo.lua
Foo = {} 

--constructor
function Foo:new(x, y)
 --the new instance
 local foo = display.newImage("foo.png") 
 - set some instance vars
 foo.x = x
 foo.y = y
 foo.name ='foo' 

 --instance method
 function fo o:speak()
 print("I am an instance and my name is ".. self.name)
 end

 --another instance method 
 function foo:moveLeft()
 self.x = self.x-1
 end

 function foo:drag(event)
 self.x = event.x< br /> self.y = event.y 
 end

 foo:addEventListener("touch", drag)

 return foo
end

--class method
function Foo:speak()
 print("I am the class Foo")
end

return Foo< /pre> 
I want the event listener on the foo object to call foo: drag the same instance. I can’t figure out how: at this point it is calling a local function called "drag" in my main.lua , And then I pass it back to the instance. Can I call the instance method directly from the listener? I am reading the listener here http://developer.anscamobile.com/reference/index/objectaddeventlistener, but I am a bit confused:/
 
Thank you, the biggest
 p>
Corona has two different types of event listeners, function listeners and table listeners. The local function you mentioned is valid because the function is called directly when the event is triggered. Corona Passing table functions is not supported, so passing drag in this instance will not work. 
 
To make it work, you need to use a table listener, as shown below:
 
 
function foo:touch(event)
 self.x = event.x
 self.y = event.y 
end

foo:addEventListener("touch", foo)
This is valid because the event listener will try to call the function in table foo with the same name as the event-in this example it is "touch ".
If you need to keep the function name as drag, you can solve this limitation by adding this function after the function definition:

player .touch = player.drag
This basically redirects the touch call to the drag function.