Whats the difference between "." and ":"?

I have seen multiple points where people have used "." in their programs and ":" in their programs, usually the latter for calling functions in tables (like a file handle). Usually, i was able to use either and thought they were identical in the syntax, but I recently came across this thread and the solution requires ":" otherwise I get a "index expected, got nil" error. So I was wondering what the syntactical difference was, and the advantages to using one over the other. Thanks for the explanation in advance!

The colon is syntactic sugar. These are the same:

object:method("argument")

object.method(object, "argument")

Yeah. The : passes the table the function belongs to as it's first argument. It can make code look a bit better (among other things)

myTableForAnObject.someFunction(myTableForAnObject, "some parameter")

V.S.

myTableForAnObject:someFunction("some parameter")

Thank you for the clear explanation! I was always wondering why people did that.

So this means that string.length("HELLO") and "HELLO":length() are the same, besides the fact I could just use #?

Death, on 22 December 2013 - 07:44 PM said:

So this means that string.length("HELLO") and "HELLO":length() are the same, besides the fact I could just use #?

yes, except for the one problem with your colon notation, I'd actually be ("HELLO"):length()

Okay, sorry about that. I was wondering if I had to do that, but internet broke and I couldn't edit the post.