=over =item caller EXPR X X X X =item caller Returns the context of the current pure perl subroutine call. In scalar context, returns the caller's package name if there I a caller (that is, if we're in a subroutine or L|/eval EXPR> or L|/require VERSION>) and the undefined value otherwise. caller never returns XS subs and they are skipped. The next pure perl sub will appear instead of the XS sub in caller's return values. In list context, caller returns # 0 1 2 my ($package, $filename, $line) = caller; Like L|/__FILE__> and L|/__LINE__>, the filename and line number returned here may be altered by the mechanism described at L. With EXPR, it returns some extra information that the debugger uses to print a stack trace. The value of EXPR indicates how many call frames to go back before the current one. # 0 1 2 3 4 my ($package, $filename, $line, $subroutine, $hasargs, # 5 6 7 8 9 10 $wantarray, $evaltext, $is_require, $hints, $bitmask, $hinthash) = caller($i); Here, $subroutine is the function that the caller called (rather than the function containing the caller). Note that $subroutine may be C<(eval)> if the frame is not a subroutine call, but an L|/eval EXPR>. In such a case additional elements $evaltext and C<$is_require> are set: C<$is_require> is true if the frame is created by a L|/require VERSION> or L|/use Module VERSION LIST> statement, $evaltext contains the text of the C statement. In particular, for an C statement, $subroutine is C<(eval)>, but $evaltext is undefined. (Note also that each L|/use Module VERSION LIST> statement creates a L|/require VERSION> frame inside an C frame.) $subroutine may also be C<(unknown)> if this particular subroutine happens to have been deleted from the symbol table. C<$hasargs> is true if a new instance of L|perlvar/@_> was set up for the frame. C<$hints> and C<$bitmask> contain pragmatic hints that the caller was compiled with. C<$hints> corresponds to L|perlvar/$^H>, and C<$bitmask> corresponds to L|perlvar/${^WARNING_BITS}>. The C<$hints> and C<$bitmask> values are subject to change between versions of Perl, and are not meant for external use. C<$hinthash> is a reference to a hash containing the value of L|perlvar/%^H> when the caller was compiled, or L|/undef EXPR> if L|perlvar/%^H> was empty. Do not modify the values of this hash, as they are the actual values stored in the optree. Note that the only types of call frames that are visible are subroutine calls and C. Other forms of context, such as C or C loops or C blocks are not considered interesting to C, as they do not alter the behaviour of the C expression. Furthermore, when called from within the DB package in list context, and with an argument, caller returns more detailed information: it sets the list variable C<@DB::args> to be the arguments with which the subroutine was invoked. Be aware that the optimizer might have optimized call frames away before L|/caller EXPR> had a chance to get the information. That means that C might not return information about the call frame you expect it to, for C<< N > 1 >>. In particular, C<@DB::args> might have information from the previous time L|/caller EXPR> was called. Be aware that setting C<@DB::args> is I, intended for debugging or generating backtraces, and should not be relied upon. In particular, as L|perlvar/@_> contains aliases to the caller's arguments, Perl does not take a copy of L|perlvar/@_>, so C<@DB::args> will contain modifications the subroutine makes to L|perlvar/@_> or its contents, not the original values at call time. C<@DB::args>, like L|perlvar/@_>, does not hold explicit references to its elements, so under certain cases its elements may have become freed and reallocated for other variables or temporary values. Finally, a side effect of the current implementation is that the effects of C can I be undone (but not C or other splicing, I not if a reference to L|perlvar/@_> has been taken, I subject to the caveat about reallocated elements), so C<@DB::args> is actually a hybrid of the current state and initial state of L|perlvar/@_>. Buyer beware. =back