trAvis - MANAGER

Edit File: Clan.pod

=head1 NAME Carp::Clan - Report errors from perspective of caller of a "clan" of modules =head1 SYNOPSIS carp - warn of errors (from perspective of caller) cluck - warn of errors with stack backtrace croak - die of errors (from perspective of caller) confess - die of errors with stack backtrace use Carp::Clan qw(^MyClan::); croak "We're outta here!"; use Carp::Clan; confess "This is how we got here!"; =head1 DESCRIPTION This module is based on "C<Carp.pm>" from Perl 5.005_03. It has been modified to skip all package names matching the pattern given in the "use" statement inside the "C<qw()>" term (or argument list). Suppose you have a family of modules or classes named "Pack::A", "Pack::B" and so on, and each of them uses "C<Carp::Clan qw(^Pack::);>" (or at least the one in which the error or warning gets raised). Thus when for example your script "tool.pl" calls module "Pack::A", and module "Pack::A" calls module "Pack::B", an exception raised in module "Pack::B" will appear to have originated in "tool.pl" where "Pack::A" was called, and not in "Pack::A" where "Pack::B" was called, as the unmodified "C<Carp.pm>" would try to make you believe C<:-)>. This works similarly if "Pack::B" calls "Pack::C" where the exception is raised, etcetera. In other words, this blames all errors in the "C<Pack::*>" modules on the user of these modules, i.e., on you. C<;-)> The skipping of a clan (or family) of packages according to a pattern describing its members is necessary in cases where these modules are not classes derived from each other (and thus when examining C<@ISA> - as in the original "C<Carp.pm>" module - doesn't help). The purpose and advantage of this is that a "clan" of modules can work together (and call each other) and throw exceptions at various depths down the calling hierarchy and still appear as a monolithic block (as though they were a single module) from the perspective of the caller. In case you just want to ward off all error messages from the module in which you "C<use Carp::Clan>", i.e., if you want to make all error messages or warnings to appear to originate from where your module was called (this is what you usually used to "C<use Carp;>" for C<;-)>), instead of in your module itself (which is what you can do with a "die" or "warn" anyway), you do not need to provide a pattern, the module will automatically provide the correct one for you. I.e., just "C<use Carp::Clan;>" without any arguments and call "carp" or "croak" as appropriate, and they will automatically defend your module against all blames! In other words, a pattern is only necessary if you want to make several modules (more than one) work together and appear as though they were only one. =head2 Forcing a Stack Trace As a debugging aid, you can force "C<Carp::Clan>" to treat a "croak" as a "confess" and a "carp" as a "cluck". In other words, force a detailed stack trace to be given. This can be very helpful when trying to understand why, or from where, a warning or error is being generated. This feature is enabled either by "importing" the non-existent symbol 'verbose', or by setting the global variable "C<$Carp::Clan::Verbose>" to a true value. You would typically enable it by saying use Carp::Clan qw(verbose); Note that you can both specify a "family pattern" and the string "verbose" inside the "C<qw()>" term (or argument list) of the "use" statement, but consider that a pattern of packages to skip is pointless when "verbose" causes a full stack trace anyway. =head1 BUGS The "C<Carp::Clan>" routines don't handle exception objects currently. If called with a first argument that is a reference, they simply call "C<die()>" or "C<warn()>", as appropriate.