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package MagicStatus; require 5.6.0; use Tie::Scalar; our @ISA = qw( Tie::Scalar ); (our $Version) = '$Revision: 1.2 $' =~ /([\d.]+)/; sub mywarn {warn @_}; sub TIESCALAR { my $class = shift; my $watch = $_[0] || undef; my $val = $_[1] || ''; my $method = $_[2] || \&mywarn; my $message = $_[3] || undef; my $self = { WATCH => $watch, VAL => $val, METHOD => $method, MESSAGE => $message, }; return bless $self, $class; } sub FETCH { shift->{VAL} } sub STORE { my $self = shift; $self->{VAL} = shift; my $value = defined $self->{WATCH} ? $self->{WATCH} : 'undef' ; my $message; if( defined $self->{MESSAGE} ) { $message = $self->{MESSAGE} } else { $message = "MagicStatus(" . $value . ") at ". (caller)[1] . ", " . (caller)[0] . ", " . (caller)[2] . "\n"; } defined $self->{WATCH} ? $self->{VAL} eq $self->{WATCH} && do{ &{ $self->{METHOD} }($message) } : defined $self->{VAL} || do{ &{ $self->{METHOD} }($message) } ; } 1; __END__ =head1 NAME MagicStatus - Scalar variable that B<warn>s on a specified value =head1 SYNOPSIS use MagicStatus; my $oops = sub { print "oops!\n"; warn shift }; tie my $status, 'MagicStatus', undef, 0, $oops, "look what i found!\ +n"; # value to watch for is set to undef, # initial value is set to 0, # method is set to $oops # message is set to "look what i found!\n" $status = 1; # status is now 1 $status = system($command, @args); # status contains the return code from $comand $status = undef; # warns with "oops!\nlook what i found!\n" $status = 'magic!'; # status is now 'magic!' =head1 DESCRIPTION This module allows you to tie a scalar variable that will B<warn> when + it is assigned a value you wish to watch. One use might be to track +and debug the return status from a function. =over 4 =item C<WATCH> Use the WATCH hash key to specify the value to watch for. If the varia +ble is set to this value, the METHOD coderef is called. If no value i +s specified for the WATCH key, it defaults to I<undef>. =item C<VAL> Use the VAL hash key to specify the initial value for the scalar varia +ble. If no initial value is set, it defaults to I<''>. =item C<METHOD> Use the METHOD hash key to specify a coderef to call if the WATCH valu +e is encountered. If no value for the METHOD key is set, it defaults +to B<\&mywarn>, which is a wrapper around B<warn>. =item C<MESSAGE> Use the MESSAGE hash key to specify a message to send to the METHOD co +deref. If no value is set, it defaults to C<MagicStatus(WATCH) at FIL +E, FUNCTION, LINE> (where FILE is the filename, FUNCTION is the funct +ion name, and LINE is the line number where the WATCH value was set. =back =head1 BUGS None known so far. Please let me know if you find any. =head1 AUTHOR particle =head1 COPYRIGHT Copyright 2002 particle. All rights reserved. This library is free software, you may redistribute it and/or modify i +t under the same terms as Perl itself. =head1 SEE ALSO perl(1), Tie::Scalar(3pm). =cut

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