diff options
author | Karl Berry <karl@freefriends.org> | 2005-12-28 00:07:27 +0000 |
---|---|---|
committer | Karl Berry <karl@freefriends.org> | 2005-12-28 00:07:27 +0000 |
commit | 30dd9f517c9c093ff3319061647a4555264f7914 (patch) | |
tree | 0d7a349bf99be5a42cc9c5a80a30f3b7136c4ccd /Master/xemtex/perl/lib/Carp.pm | |
parent | 08ab8dce83f53b0f915cb66a37bbc8478b22c307 (diff) |
trunk
git-svn-id: svn://tug.org/texlive/trunk@9 c570f23f-e606-0410-a88d-b1316a301751
Diffstat (limited to 'Master/xemtex/perl/lib/Carp.pm')
-rw-r--r-- | Master/xemtex/perl/lib/Carp.pm | 196 |
1 files changed, 196 insertions, 0 deletions
diff --git a/Master/xemtex/perl/lib/Carp.pm b/Master/xemtex/perl/lib/Carp.pm new file mode 100644 index 00000000000..6199f894487 --- /dev/null +++ b/Master/xemtex/perl/lib/Carp.pm @@ -0,0 +1,196 @@ +package Carp; + +our $VERSION = '1.01'; + +=head1 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 + +=head1 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"); + +=head1 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: + +=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 + +As a debugging aid, you can force Carp to treat a croak as a confess +and a carp as a cluck across I<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 C<MCarp=verbose> in the PERL5OPT +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 is heavily used. Be small. Be fast. Be good. + +# Comments added by Andy Wardley <abw@kfs.org> 09-Apr-98, based on an +# _almost_ complete understanding of the package. Corrections and +# comments are welcome. + +# 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 + +require Exporter; +@ISA = ('Exporter'); +@EXPORT = qw(confess croak carp); +@EXPORT_OK = qw(cluck verbose longmess shortmess); +@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 { + { local $@; require Carp::Heavy; } # XXX fix require to not clear $@? + # 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(@_); + } +} + + +# 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 + { local $@; require Carp::Heavy; } # XXX fix require to not clear $@? + # Icky backwards compatibility wrapper. :-( + my $call_pack = caller(); + local @CARP_NOT = caller(); + shortmess_heavy(@_); +} + + +# 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; |