Report errors from perspective of caller of a "clan" of modules
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!";
This module is based on "\*(C`Carp.pm\*(C'\*(L" from Perl 5.005_03. It has been modified to skip all package names matching the pattern given in the \*(R"use\*(L" statement inside the \*(R"\*(C`qw()\*(C'" term (or argument list).
Suppose you have a family of modules or classes named \*(L"Pack::A\*(R", \*(L"Pack::B\*(R" and so on, and each of them uses "\*(C`Carp::Clan qw(^Pack::);\*(C'" (or at least the one in which the error or warning gets raised).
Thus when for example your script \*(L"tool.pl\*(R" calls module \*(L"Pack::A\*(R", and module \*(L"Pack::A\*(R" calls module \*(L"Pack::B\*(R", an exception raised in module \*(L"Pack::B\*(R" will appear to have originated in \*(L"tool.pl\*(R" where \*(L"Pack::A\*(R" was called, and not in \*(L"Pack::A\*(R" where \*(L"Pack::B\*(R" was called, as the unmodified "\*(C`Carp.pm\*(C'" would try to make you believe \*(C`:-)\*(C'.
This works similarly if \*(L"Pack::B\*(R" calls \*(L"Pack::C\*(R" where the exception is raised, etcetera.
In other words, this blames all errors in the "\*(C`Pack::*\*(C'" modules on the user of these modules, i.e., on you. \*(C`;-)\*(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 @ISA - as in the original "\*(C`Carp.pm\*(C'" module - doesn't help).
The purpose and advantage of this is that a \*(L"clan\*(R" 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\*(C'\*(L", 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 \*(R"\*(C`use Carp;\*(C'" for \*(C`;-)\*(C'), instead of in your module itself (which is what you can do with a \*(L"die\*(R" or \*(L"warn\*(R" 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;\*(C'\*(L" without any arguments and call \*(R"carp\*(L" or \*(R"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.
As a debugging aid, you can force "\*(C`Carp::Clan\*(C'\*(L" to treat a \*(R"croak\*(L" as a \*(R"confess\*(L" and a \*(R"carp\*(L" as a \*(R"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 \*(L"importing\*(R" the non-existent symbol 'verbose', or by setting the global variable "$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 \*(L"family pattern\*(R" and the string \*(L"verbose\*(R" inside the "\*(C`qw()\*(C'\*(L" term (or argument list) of the \*(R"use\*(L" statement, but consider that a pattern of packages to skip is pointless when \*(R"verbose" causes a full stack trace anyway.
The "\*(C`Carp::Clan\*(C'\*(L" routines don't handle exception objects currently. If called with a first argument that is a reference, they simply call \*(R"\*(C`die()\*(C'\*(L" or \*(R"\*(C`warn()\*(C'", as appropriate.