/IronPython_Main/Runtime/Tests/LinqDlrTests/testenv/perl/lib/exceptions.pl

# exceptions.pl

# tchrist@convex.com

#

# 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.

#

# 

# 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;