No matter what the argument, the debug.getinfo function will return a table. This table will contain information about the function being inspected. When called with an integer, the return table will contain the following fields/variables:

• source: Where the function is defined. This will contain the name of the file that a function is defined in.
• short_src: A short textual version of the function, up to 60 characters.
• linedefined: The first line of the source file where the function was defined.
• lastlinedefined: The last line in the source file where the function was defined.
• what: If the function is a "Lua" or a "C" function, the appropriate string will be returned.
• name: Lua's best guess at the name of the function. In Lua, functions can be assigned to multiple variables, so the name really is a guess most of the time.
• namewhat: What the name field is: a "global" variable, a "local" variable, a "method", a "field", or unknown ("").
• nups: The number of up values for the function.
• activelines: The number of lines a function contains. White spaces and comments are ignored.
• func: The actual function; you can call this.