package Carp;
-our $VERSION = '1.00';
+our $VERSION = '1.01';
=head1 NAME
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
+
=head1 SYNOPSIS
use Carp;
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");
+
=head1 DESCRIPTION
The Carp routines are useful in your own modules because
-they act like die() or warn(), but report where the error
-was in the code they were called from. Thus if you have a
-routine Foo() that has a carp() in it, then the carp()
-will report the error as occurring where Foo() was called,
-not where carp() was called.
+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:
+
+=over 4
+
+=item 1.
+
+Any call from a package to itself is safe.
+
+=item 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.
+
+=item 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".
+
+=item 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.)
+
+=item 5.
+
+Any call to Carp is safe. (This rule is what keeps it from
+reporting the error where you call carp/croak/shortmess.)
+
+=back
=head2 Forcing a Stack Trace
perl -MCarp=verbose script.pl
-or by including the string C<MCarp=verbose> in the L<PERL5OPT>
+or by including the string C<MCarp=verbose> in the PERL5OPT
environment variable.
=head1 BUGS
# _almost_ complete understanding of the package. Corrections and
# comments are welcome.
-# The $CarpLevel variable can be set to "strip off" extra caller levels for
-# those times when Carp calls are buried inside other functions. The
+# The members of %Internal are packages that are internal to perl.
+# Carp will not report errors from within these packages if it
+# can. The members of %CarpInternal are internal to Perl's warning
+# system. Carp will not report errors from within these packages
+# either, and will not report calls *to* these packages for carp and
+# croak. They replace $CarpLevel, which is deprecated. The
# $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval
# text and function arguments should be formatted when printed.
+$CarpInternal{Carp}++;
+$CarpInternal{warnings}++;
$CarpLevel = 0; # How many extra package levels to skip on carp.
+ # How many calls to skip on confess.
+ # Reconciling these notions is hard, use
+ # %Internal and %CarpInternal instead.
$MaxEvalLen = 0; # How much eval '...text...' to show. 0 = all.
$MaxArgLen = 64; # How much of each argument to print. 0 = all.
$MaxArgNums = 8; # How many arguments to print. 0 = all.
$Verbose = 0; # If true then make shortmess call longmess instead
-$CarpInternal{Carp}++;
-
require Exporter;
@ISA = ('Exporter');
@EXPORT = qw(confess croak carp);
-@EXPORT_OK = qw(cluck verbose);
+@EXPORT_OK = qw(cluck verbose longmess shortmess);
@EXPORT_FAIL = qw(verbose); # hook to enable verbose mode
sub longmess {
{ local $@; require Carp::Heavy; } # XXX fix require to not clear $@?
- goto &longmess_heavy;
+ # Icky backwards compatibility wrapper. :-(
+ my $call_pack = caller();
+ if ($Internal{$call_pack} or $CarpInternal{$call_pack}) {
+ return longmess_heavy(@_);
+ }
+ else {
+ local $CarpLevel = $CarpLevel + 1;
+ return longmess_heavy(@_);
+ }
}
sub shortmess { # Short-circuit &longmess if called via multiple packages
{ local $@; require Carp::Heavy; } # XXX fix require to not clear $@?
- goto &shortmess_heavy;
+ # Icky backwards compatibility wrapper. :-(
+ my $call_pack = caller();
+ local @CARP_NOT = caller();
+ shortmess_heavy(@_);
}
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