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Carp(3)
NAME
  carp	  - warn of errors (from perspective of caller)

  cluck	  - warn of errors with stack backtrace
	    (not exported by default)

  croak	  - die of errors (from perspective of caller)

  confess - die of errors with stack backtrace

  shortmess - return the message that carp and croak produce

  longmess - return the message that cluck and confess produce

SYNOPSIS
      use Carp;
      croak "We're outta here!";

      use Carp qw(cluck);
      cluck "This is how we got here!";

      print FH Carp::shortmess("This will have caller's details added");
      print FH Carp::longmess("This will have stack backtrace added");

DESCRIPTION
  The Carp routines are useful in your own modules because they act like
  die() or warn(), but with a message which is more likely to be useful to a
  user of your module.	In the case of cluck, confess, and longmess that
  context is a summary of every call in the call-stack.	 For a shorter
  message you can use carp, croak or shortmess which report the error as
  being from where your module was called.  There is no guarantee that that
  is where the error was, but it is a good educated guess.

  Here is a more complete description of how shortmess works.  What it does
  is search the call-stack for a function call stack where it hasn't been
  told that there shouldn't be an error.  If every call is marked safe, it
  then gives up and gives a full stack backtrace instead.  In other words it
  presumes that the first likely looking potential suspect is guilty.  Its
  rules for telling whether a call shouldn't generate errors work as follows:

  1.  Any call from a package to itself is safe.

  2.  Packages claim that there won't be errors on calls to or from packages
      explicitly marked as safe by inclusion in @CARP_NOT, or (if that array
      is empty) @ISA.  The ability to override what @ISA says is new in 5.8.

  3.  The trust in item 2 is transitive.  If A trusts B, and B trusts C, then
      A trusts C.  So if you do not override @ISA with @CARP_NOT, then this
      trust relationship is identical to, "inherits from".

  4.  Any call from an internal Perl module is safe.  (Nothing keeps user
      modules from marking themselves as internal to Perl, but this practice
      is discouraged.)

  5.  Any call to Carp is safe.	 (This rule is what keeps it from reporting
      the error where you call carp/croak/shortmess.)

  Forcing a Stack Trace

  As a debugging aid, you can force Carp to treat a croak as a confess and a
  carp as a cluck across all modules. 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 by 'importing' the non-existent symbol 'verbose'.
  You would typically enable it by saying

      perl -MCarp=verbose script.pl

  or by including the string "MCarp=verbose" in the PERL5OPT environment
  variable.

BUGS
  The Carp routines don't handle exception objects currently.  If called with
  a first argument that is a reference, they simply call die() or warn(), as
  appropriate.

Index for Section 3

Alphabetical listing for C

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