The Perl debuger is a wonderful tool. By setting its warnlevel or dielevel you can get it to print out a stack trace on a warn or a die. But what if you want to breakpoint on those events? This snippet (when put into a ./.perldb or ~/.perldb file) allows you to set breakpoints (after printing the warn/dielevel stack traces, if any) on these events. Just type sow to stop on warn, or sod to stop on die.

update: made it pass args to oldWarn/oldDie

# Stop on warn (sow)
$DB::oldWarn = $SIG{__WARN__};
$DB::alias{sow} = 's/^sow/\$SIG{__WARN__} = sub { \$DB::oldWarn->(@_) 
+if (\$DB::oldWarn); \$DB::single = 1 }/';
# Stop on die (sod)
$DB::oldDie = $SIG{__DIE__};
$DB::alias{sod} = 's/^sod/\$SIG{__DIE__} = sub { \$DB::oldDie->(@_) if
+ (\$DB::oldDie); \$DB::single = 1 }/';
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