1998-09-09 07:00:04 +00:00
|
|
|
# exceptions.pl
|
|
|
|
|
# tchrist@convex.com
|
2000-06-25 11:04:01 +00:00
|
|
|
#
|
|
|
|
|
# This library is no longer being maintained, and is included for backward
|
|
|
|
|
# compatibility with Perl 4 programs which may require it.
|
|
|
|
|
#
|
|
|
|
|
# In particular, this should not be used as an example of modern Perl
|
|
|
|
|
# programming techniques.
|
|
|
|
|
#
|
1998-09-09 07:00:04 +00:00
|
|
|
#
|
|
|
|
|
# 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;
|
