require(),and the undefined value otherwise. In a list context, returns
($package, $filename, $line) = caller;
With EXPR, it returns some extra information that the debugger uses to print a stack trace. The value of EXPR indicates how many call frames to go back before the current one.
($package, $filename, $line, $subroutine, $hasargs, $wantarray, $evaltext, $is_require) = caller($i);
$subroutine may be
"(eval)" if the frame is not a subroutine call, but an eval. In such a case additional elements
$is_require are set:
$is_require is true if the
frame is created by a
require or use statement,
$evaltext contains the text of the
eval EXPR statement. In particular, for a
eval BLOCK statement,
$evaltext is undefined. (Note also that each use statement creates a require frame inside an
eval EXPR) frame.
Furthermore, when called from within the DB package, caller returns more detailed information: it sets the list variable @DB::args to be the arguments with which the subroutine was invoked.