125 lines
4.1 KiB
Perl
125 lines
4.1 KiB
Perl
package Carp;
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=head1 NAME
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carp - warn of errors (from perspective of caller)
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cluck - warn of errors with stack backtrace
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(not exported by default)
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croak - die of errors (from perspective of caller)
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confess - die of errors with stack backtrace
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=head1 SYNOPSIS
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use Carp;
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croak "We're outta here!";
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use Carp qw(cluck);
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cluck "This is how we got here!";
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=head1 DESCRIPTION
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The Carp routines are useful in your own modules because
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they act like die() or warn(), but report where the error
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was in the code they were called from. Thus if you have a
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routine Foo() that has a carp() in it, then the carp()
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will report the error as occurring where Foo() was called,
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not where carp() was called.
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=head2 Forcing a Stack Trace
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As a debugging aid, you can force Carp to treat a croak as a confess
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and a carp as a cluck across I<all> modules. In other words, force a
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detailed stack trace to be given. This can be very helpful when trying
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to understand why, or from where, a warning or error is being generated.
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This feature is enabled by 'importing' the non-existent symbol
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'verbose'. You would typically enable it by saying
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perl -MCarp=verbose script.pl
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or by including the string C<MCarp=verbose> in the L<PERL5OPT>
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environment variable.
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=head1 BUGS
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The Carp routines don't handle exception objects currently.
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If called with a first argument that is a reference, they simply
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call die() or warn(), as appropriate.
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=cut
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# This package is heavily used. Be small. Be fast. Be good.
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# Comments added by Andy Wardley <abw@kfs.org> 09-Apr-98, based on an
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# _almost_ complete understanding of the package. Corrections and
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# comments are welcome.
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# The $CarpLevel variable can be set to "strip off" extra caller levels for
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# those times when Carp calls are buried inside other functions. The
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# $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval
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# text and function arguments should be formatted when printed.
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$CarpLevel = 0; # How many extra package levels to skip on carp.
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$MaxEvalLen = 0; # How much eval '...text...' to show. 0 = all.
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$MaxArgLen = 64; # How much of each argument to print. 0 = all.
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$MaxArgNums = 8; # How many arguments to print. 0 = all.
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$Verbose = 0; # If true then make shortmess call longmess instead
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require Exporter;
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@ISA = ('Exporter');
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@EXPORT = qw(confess croak carp);
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@EXPORT_OK = qw(cluck verbose);
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@EXPORT_FAIL = qw(verbose); # hook to enable verbose mode
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# if the caller specifies verbose usage ("perl -MCarp=verbose script.pl")
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# then the following method will be called by the Exporter which knows
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# to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word
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# 'verbose'.
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sub export_fail {
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shift;
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$Verbose = shift if $_[0] eq 'verbose';
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return @_;
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}
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# longmess() crawls all the way up the stack reporting on all the function
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# calls made. The error string, $error, is originally constructed from the
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# arguments passed into longmess() via confess(), cluck() or shortmess().
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# This gets appended with the stack trace messages which are generated for
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# each function call on the stack.
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sub longmess {
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{ local $@; require Carp::Heavy; } # XXX fix require to not clear $@?
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goto &longmess_heavy;
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}
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# shortmess() is called by carp() and croak() to skip all the way up to
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# the top-level caller's package and report the error from there. confess()
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# and cluck() generate a full stack trace so they call longmess() to
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# generate that. In verbose mode shortmess() calls longmess() so
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# you always get a stack trace
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sub shortmess { # Short-circuit &longmess if called via multiple packages
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{ local $@; require Carp::Heavy; } # XXX fix require to not clear $@?
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goto &shortmess_heavy;
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}
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# the following four functions call longmess() or shortmess() depending on
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# whether they should generate a full stack trace (confess() and cluck())
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# or simply report the caller's package (croak() and carp()), respectively.
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# confess() and croak() die, carp() and cluck() warn.
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sub croak { die shortmess @_ }
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sub confess { die longmess @_ }
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sub carp { warn shortmess @_ }
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sub cluck { warn longmess @_ }
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1;
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