X-Git-Url: http://git.shadowcat.co.uk/gitweb/gitweb.cgi?a=blobdiff_plain;f=lib%2FCarp.pm;h=43524ddbe54b3be0ffee749b92f2a42c730d8521;hb=a85d93d9d5c06911d843f281439a8d3e65aeb165;hp=2d857ba4e769453afc85334b2231802c5a78e491;hpb=c1bce5d7c4f10bb970b094ec986540c244295278;p=p5sagit%2Fp5-mst-13.2.git diff --git a/lib/Carp.pm b/lib/Carp.pm index 2d857ba..43524dd 100644 --- a/lib/Carp.pm +++ b/lib/Carp.pm @@ -2,9 +2,12 @@ package Carp; =head1 NAME -carp - warn of errors (from perspective of caller) +carp - warn of errors (from perspective of caller) -croak - die 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 @@ -13,6 +16,9 @@ confess - die of errors with stack backtrace use Carp; croak "We're outta here!"; + use Carp qw(cluck); + cluck "This is how we got here!"; + =head1 DESCRIPTION The Carp routines are useful in your own modules because @@ -22,55 +28,97 @@ 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. +=head2 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 I 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 C in the L +environment variable. + +=head1 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. + =cut -# This package implements handy routines for modules that wish to throw -# exceptions outside of the current package. +# This package is heavily used. Be small. Be fast. Be good. + +# Comments added by Andy Wardley 09-Apr-98, based on an +# _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 +# $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval +# text and function arguments should be formatted when printed. $CarpLevel = 0; # How many extra package levels to skip on carp. +$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 require Exporter; -@ISA = Exporter; +@ISA = ('Exporter'); @EXPORT = qw(confess croak carp); +@EXPORT_OK = qw(cluck verbose); +@EXPORT_FAIL = qw(verbose); # hook to enable verbose mode + + +# if the caller specifies verbose usage ("perl -MCarp=verbose script.pl") +# then the following method will be called by the Exporter which knows +# to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word +# 'verbose'. + +sub export_fail { + shift; + $Verbose = shift if $_[0] eq 'verbose'; + return @_; +} + + +# longmess() crawls all the way up the stack reporting on all the function +# calls made. The error string, $error, is originally constructed from the +# arguments passed into longmess() via confess(), cluck() or shortmess(). +# This gets appended with the stack trace messages which are generated for +# each function call on the stack. sub longmess { - my $error = shift; - my $mess = ""; - my $i = 1 + $CarpLevel; - my ($pack,$file,$line,$sub); - while (($pack,$file,$line,$sub) = caller($i++)) { - if ($error =~ m/\n$/) { - $mess .= $error; - } else { - $mess .= "\t$sub " if $error eq "called"; - $mess .= "$error at $file line $line\n"; - } - $error = "called"; - } - $mess || $error; + { local $@; require Carp::Heavy; } # XXX fix require to not clear $@? + goto &longmess_heavy; } + +# shortmess() is called by carp() and croak() to skip all the way up to +# the top-level caller's package and report the error from there. confess() +# and cluck() generate a full stack trace so they call longmess() to +# generate that. In verbose mode shortmess() calls longmess() so +# you always get a stack trace + sub shortmess { # Short-circuit &longmess if called via multiple packages - my $error = $_[0]; # Instead of "shift" - my ($curpack) = caller(1); - my $extra = $CarpLevel; - my $i = 2; - my ($pack,$file,$line,$sub); - while (($pack,$file,$line,$sub) = caller($i++)) { - if ($pack ne $curpack) { - if ($extra-- > 0) { - $curpack = $pack; - } - else { - return "$error at $file line $line\n"; - } - } - } - goto &longmess; + { local $@; require Carp::Heavy; } # XXX fix require to not clear $@? + goto &shortmess_heavy; } -sub confess { die longmess @_; } -sub croak { die shortmess @_; } -sub carp { warn shortmess @_; } + +# the following four functions call longmess() or shortmess() depending on +# whether they should generate a full stack trace (confess() and cluck()) +# or simply report the caller's package (croak() and carp()), respectively. +# confess() and croak() die, carp() and cluck() warn. + +sub croak { die shortmess @_ } +sub confess { die longmess @_ } +sub carp { warn shortmess @_ } +sub cluck { warn longmess @_ } 1;