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