diff options
Diffstat (limited to 'gnu/usr.bin/perl/lib/exceptions.pl')
-rw-r--r-- | gnu/usr.bin/perl/lib/exceptions.pl | 54 |
1 files changed, 54 insertions, 0 deletions
diff --git a/gnu/usr.bin/perl/lib/exceptions.pl b/gnu/usr.bin/perl/lib/exceptions.pl new file mode 100644 index 0000000..02c4498 --- /dev/null +++ b/gnu/usr.bin/perl/lib/exceptions.pl @@ -0,0 +1,54 @@ +# exceptions.pl +# tchrist@convex.com +# +# Here's a little code I use for exception handling. It's really just +# glorfied eval/die. The way to use use it is when you might otherwise +# exit, use &throw to raise an exception. The first enclosing &catch +# handler looks at the exception and decides whether it can catch this kind +# (catch takes a list of regexps to catch), and if so, it returns the one it +# caught. If it *can't* catch it, then it will reraise the exception +# for someone else to possibly see, or to die otherwise. +# +# I use oddly named variables in order to make darn sure I don't conflict +# with my caller. I also hide in my own package, and eval the code in his. +# +# The EXCEPTION: prefix is so you can tell whether it's a user-raised +# exception or a perl-raised one (eval error). +# +# --tom +# +# examples: +# if (&catch('/$user_input/', 'regexp', 'syntax error') { +# warn "oops try again"; +# redo; +# } +# +# if ($error = &catch('&subroutine()')) { # catches anything +# +# &throw('bad input') if /^$/; + +sub catch { + package exception; + local($__code__, @__exceptions__) = @_; + local($__package__) = caller; + local($__exception__); + + eval "package $__package__; $__code__"; + if ($__exception__ = &'thrown) { + for (@__exceptions__) { + return $__exception__ if /$__exception__/; + } + &'throw($__exception__); + } +} + +sub throw { + local($exception) = @_; + die "EXCEPTION: $exception\n"; +} + +sub thrown { + $@ =~ /^(EXCEPTION: )+(.+)/ && $2; +} + +1; |