Return the full pathname of a file, relative to $initial_directory.
TODO: The user must not chdir to an alternate directory before requiring this file.
TODO: This does not check to see if the file does not exist.
TODO: This does not check to see if the file is a shared object.
TODO: This does not check to see if the file is "(eval)".
Returns: the full pathname of $0, or nil if it cannot be determined.
Parse a caller string and break it into its components.
Note: If the user decides to redefine caller() to output data in a different format, then the results will be undefined.
Returns: file (String), lineno (Integer), method (Symbol)
Return a string representing the line at the given caller level.
|level||the level of the line desired, relative to the the method that called caller_line.|
Returns: a string holding the contents of the desired line.