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-
- =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.
-
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