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1 | package Carp; |
2 | |
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3 | our $VERSION = '1.00'; |
4 | |
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5 | =head1 NAME |
6 | |
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7 | carp - warn of errors (from perspective of caller) |
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8 | |
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9 | cluck - warn of errors with stack backtrace |
10 | (not exported by default) |
11 | |
12 | croak - die of errors (from perspective of caller) |
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13 | |
14 | confess - die of errors with stack backtrace |
15 | |
16 | =head1 SYNOPSIS |
17 | |
18 | use Carp; |
19 | croak "We're outta here!"; |
20 | |
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21 | use Carp qw(cluck); |
22 | cluck "This is how we got here!"; |
23 | |
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24 | =head1 DESCRIPTION |
25 | |
26 | The Carp routines are useful in your own modules because |
27 | they act like die() or warn(), but report where the error |
28 | was in the code they were called from. Thus if you have a |
29 | routine Foo() that has a carp() in it, then the carp() |
30 | will report the error as occurring where Foo() was called, |
31 | not where carp() was called. |
32 | |
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33 | =head2 Forcing a Stack Trace |
34 | |
35 | As a debugging aid, you can force Carp to treat a croak as a confess |
36 | and a carp as a cluck across I<all> modules. In other words, force a |
37 | detailed stack trace to be given. This can be very helpful when trying |
38 | to understand why, or from where, a warning or error is being generated. |
39 | |
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40 | This feature is enabled by 'importing' the non-existent symbol |
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41 | 'verbose'. You would typically enable it by saying |
42 | |
43 | perl -MCarp=verbose script.pl |
44 | |
45 | or by including the string C<MCarp=verbose> in the L<PERL5OPT> |
46 | environment variable. |
47 | |
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48 | =head1 BUGS |
49 | |
50 | The Carp routines don't handle exception objects currently. |
51 | If called with a first argument that is a reference, they simply |
52 | call die() or warn(), as appropriate. |
53 | |
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54 | =cut |
55 | |
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56 | # This package is heavily used. Be small. Be fast. Be good. |
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57 | |
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58 | # Comments added by Andy Wardley <abw@kfs.org> 09-Apr-98, based on an |
59 | # _almost_ complete understanding of the package. Corrections and |
60 | # comments are welcome. |
61 | |
62 | # The $CarpLevel variable can be set to "strip off" extra caller levels for |
63 | # those times when Carp calls are buried inside other functions. The |
64 | # $Max(EvalLen|(Arg(Len|Nums)) variables are used to specify how the eval |
65 | # text and function arguments should be formatted when printed. |
66 | |
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67 | $CarpLevel = 0; # How many extra package levels to skip on carp. |
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68 | $MaxEvalLen = 0; # How much eval '...text...' to show. 0 = all. |
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69 | $MaxArgLen = 64; # How much of each argument to print. 0 = all. |
70 | $MaxArgNums = 8; # How many arguments to print. 0 = all. |
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71 | $Verbose = 0; # If true then make shortmess call longmess instead |
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72 | |
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73 | $CarpInternal{Carp}++; |
74 | |
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75 | require Exporter; |
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76 | @ISA = ('Exporter'); |
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77 | @EXPORT = qw(confess croak carp); |
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78 | @EXPORT_OK = qw(cluck verbose); |
79 | @EXPORT_FAIL = qw(verbose); # hook to enable verbose mode |
80 | |
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81 | |
82 | # if the caller specifies verbose usage ("perl -MCarp=verbose script.pl") |
83 | # then the following method will be called by the Exporter which knows |
84 | # to do this thanks to @EXPORT_FAIL, above. $_[1] will contain the word |
85 | # 'verbose'. |
86 | |
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87 | sub export_fail { |
88 | shift; |
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89 | $Verbose = shift if $_[0] eq 'verbose'; |
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90 | return @_; |
91 | } |
92 | |
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93 | |
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94 | # longmess() crawls all the way up the stack reporting on all the function |
95 | # calls made. The error string, $error, is originally constructed from the |
96 | # arguments passed into longmess() via confess(), cluck() or shortmess(). |
97 | # This gets appended with the stack trace messages which are generated for |
98 | # each function call on the stack. |
99 | |
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100 | sub longmess { |
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101 | { local $@; require Carp::Heavy; } # XXX fix require to not clear $@? |
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102 | goto &longmess_heavy; |
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103 | } |
104 | |
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105 | |
106 | # shortmess() is called by carp() and croak() to skip all the way up to |
107 | # the top-level caller's package and report the error from there. confess() |
108 | # and cluck() generate a full stack trace so they call longmess() to |
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109 | # generate that. In verbose mode shortmess() calls longmess() so |
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110 | # you always get a stack trace |
111 | |
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112 | sub shortmess { # Short-circuit &longmess if called via multiple packages |
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113 | { local $@; require Carp::Heavy; } # XXX fix require to not clear $@? |
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114 | goto &shortmess_heavy; |
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115 | } |
116 | |
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117 | |
118 | # the following four functions call longmess() or shortmess() depending on |
119 | # whether they should generate a full stack trace (confess() and cluck()) |
120 | # or simply report the caller's package (croak() and carp()), respectively. |
121 | # confess() and croak() die, carp() and cluck() warn. |
122 | |
123 | sub croak { die shortmess @_ } |
124 | sub confess { die longmess @_ } |
125 | sub carp { warn shortmess @_ } |
126 | sub cluck { warn longmess @_ } |
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127 | |
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128 | 1; |