lib/English.pm

   1 package English;
   2
   3 our $VERSION = '1.03';
   4
   5 require Exporter;
   6 @ISA = (Exporter);
   7
   8 =head1 NAME
   9
  10 English - use nice English (or awk) names for ugly punctuation variables
  11
  12 =head1 SYNOPSIS
  13
  14     use English qw( -no_match_vars ) ;  # Avoids regex performance penalty
  15     use English;
  16     ...
  17     if ($ERRNO =~ /denied/) { ... }
  18
  19 =head1 DESCRIPTION
  20
  21 This module provides aliases for the built-in variables whose
  22 names no one seems to like to read.  Variables with side-effects
  23 which get triggered just by accessing them (like $0) will still
  24 be affected.
  25
  26 For those variables that have an B<awk> version, both long
  27 and short English alternatives are provided.  For example,
  28 the C<$/> variable can be referred to either $RS or
  29 $INPUT_RECORD_SEPARATOR if you are using the English module.
  30
  31 See L<perlvar> for a complete list of these.
  32
  33 =head1 PERFORMANCE
  34
  35 This module can provoke sizeable inefficiencies for regular expressions,
  36 due to unfortunate implementation details.  If performance matters in
  37 your application and you don't need $PREMATCH, $MATCH, or $POSTMATCH,
  38 try doing
  39
  40    use English qw( -no_match_vars ) ;
  41
  42 .  B<It is especially important to do this in modules to avoid penalizing
  43 all applications which use them.>
  44
  45 =cut
  46
  47 no warnings;
  48
  49 my $globbed_match ;
  50
  51 # Grandfather $NAME import
  52 sub import {
  53     my $this = shift;
  54     my @list = grep { ! /^-no_match_vars$/ } @_ ;
  55     local $Exporter::ExportLevel = 1;
  56     if ( @_ == @list ) {
  57         *EXPORT = \@COMPLETE_EXPORT ;
  58         $globbed_match ||= (
  59             eval q{
  60                 *MATCH                          = *&    ;
  61                 *PREMATCH                       = *`    ;
  62                 *POSTMATCH                      = *'    ;
  63                 1 ;
  64                }
  65             || do {
  66                 require Carp ;
  67                 Carp::croak("Can't create English for match leftovers: $@") ;
  68             }
  69         ) ;
  70     }
  71     else {
  72         *EXPORT = \@MINIMAL_EXPORT ;
  73     }
  74     Exporter::import($this,grep {s/^\$/*/} @list);
  75 }
  76
  77 @MINIMAL_EXPORT = qw(
  78         *ARG
  79         *LAST_PAREN_MATCH
  80         *INPUT_LINE_NUMBER
  81         *NR
  82         *INPUT_RECORD_SEPARATOR
  83         *RS
  84         *OUTPUT_AUTOFLUSH
  85         *OUTPUT_FIELD_SEPARATOR
  86         *OFS
  87         *OUTPUT_RECORD_SEPARATOR
  88         *ORS
  89         *LIST_SEPARATOR
  90         *SUBSCRIPT_SEPARATOR
  91         *SUBSEP
  92         *FORMAT_PAGE_NUMBER
  93         *FORMAT_LINES_PER_PAGE
  94         *FORMAT_LINES_LEFT
  95         *FORMAT_NAME
  96         *FORMAT_TOP_NAME
  97         *FORMAT_LINE_BREAK_CHARACTERS
  98         *FORMAT_FORMFEED
  99         *CHILD_ERROR
 100         *OS_ERROR
 101         *ERRNO
 102         *EXTENDED_OS_ERROR
 103         *EVAL_ERROR
 104         *PROCESS_ID
 105         *PID
 106         *REAL_USER_ID
 107         *UID
 108         *EFFECTIVE_USER_ID
 109         *EUID
 110         *REAL_GROUP_ID
 111         *GID
 112         *EFFECTIVE_GROUP_ID
 113         *EGID
 114         *PROGRAM_NAME
 115         *PERL_VERSION
 116         *ACCUMULATOR
 117         *COMPILING
 118         *DEBUGGING
 119         *SYSTEM_FD_MAX
 120         *INPLACE_EDIT
 121         *PERLDB
 122         *BASETIME
 123         *WARNING
 124         *EXECUTABLE_NAME
 125         *OSNAME
 126         *LAST_REGEXP_CODE_RESULT
 127         *EXCEPTIONS_BEING_CAUGHT
 128         *LAST_SUBMATCH_RESULT
 129         @LAST_MATCH_START
 130         @LAST_MATCH_END
 131 );
 132
 133
 134 @MATCH_EXPORT = qw(
 135         *MATCH
 136         *PREMATCH
 137         *POSTMATCH
 138 );
 139
 140 @COMPLETE_EXPORT = ( @MINIMAL_EXPORT, @MATCH_EXPORT ) ;
 141
 142 # The ground of all being. @ARG is deprecated (5.005 makes @_ lexical)
 143
 144         *ARG                                    = *_    ;
 145
 146 # Matching.
 147
 148         *LAST_PAREN_MATCH                       = *+    ;
 149         *LAST_SUBMATCH_RESULT                   = *^N ;
 150         *LAST_MATCH_START                       = *-{ARRAY} ;
 151         *LAST_MATCH_END                         = *+{ARRAY} ;
 152
 153 # Input.
 154
 155         *INPUT_LINE_NUMBER                      = *.    ;
 156             *NR                                 = *.    ;
 157         *INPUT_RECORD_SEPARATOR                 = */    ;
 158             *RS                                 = */    ;
 159
 160 # Output.
 161
 162         *OUTPUT_AUTOFLUSH                       = *|    ;
 163         *OUTPUT_FIELD_SEPARATOR                 = *,    ;
 164             *OFS                                = *,    ;
 165         *OUTPUT_RECORD_SEPARATOR                = *\    ;
 166             *ORS                                = *\    ;
 167
 168 # Interpolation "constants".
 169
 170         *LIST_SEPARATOR                         = *"    ;
 171         *SUBSCRIPT_SEPARATOR                    = *;    ;
 172             *SUBSEP                             = *;    ;
 173
 174 # Formats
 175
 176         *FORMAT_PAGE_NUMBER                     = *%    ;
 177         *FORMAT_LINES_PER_PAGE                  = *=    ;
 178         *FORMAT_LINES_LEFT                      = *-    ;
 179         *FORMAT_NAME                            = *~    ;
 180         *FORMAT_TOP_NAME                        = *^    ;
 181         *FORMAT_LINE_BREAK_CHARACTERS           = *:    ;
 182         *FORMAT_FORMFEED                        = *^L   ;
 183
 184 # Error status.
 185
 186         *CHILD_ERROR                            = *?    ;
 187         *OS_ERROR                               = *!    ;
 188             *ERRNO                              = *!    ;
 189         *OS_ERROR                               = *!    ;
 190             *ERRNO                              = *!    ;
 191         *EXTENDED_OS_ERROR                      = *^E   ;
 192         *EVAL_ERROR                             = *@    ;
 193
 194 # Process info.
 195
 196         *PROCESS_ID                             = *$    ;
 197             *PID                                = *$    ;
 198         *REAL_USER_ID                           = *<    ;
 199             *UID                                = *<    ;
 200         *EFFECTIVE_USER_ID                      = *>    ;
 201             *EUID                               = *>    ;
 202         *REAL_GROUP_ID                          = *(    ;
 203             *GID                                = *(    ;
 204         *EFFECTIVE_GROUP_ID                     = *)    ;
 205             *EGID                               = *)    ;
 206         *PROGRAM_NAME                           = *0    ;
 207
 208 # Internals.
 209
 210         *PERL_VERSION                           = *^V   ;
 211         *ACCUMULATOR                            = *^A   ;
 212         *COMPILING                              = *^C   ;
 213         *DEBUGGING                              = *^D   ;
 214         *SYSTEM_FD_MAX                          = *^F   ;
 215         *INPLACE_EDIT                           = *^I   ;
 216         *PERLDB                                 = *^P   ;
 217         *LAST_REGEXP_CODE_RESULT                = *^R   ;
 218         *EXCEPTIONS_BEING_CAUGHT                = *^S   ;
 219         *BASETIME                               = *^T   ;
 220         *WARNING                                = *^W   ;
 221         *EXECUTABLE_NAME                        = *^X   ;
 222         *OSNAME                                 = *^O   ;
 223
 224 # Deprecated.
 225
 226 #       *ARRAY_BASE                             = *[    ;
 227 #       *OFMT                                   = *#    ;
 228 #       *OLD_PERL_VERSION                       = *]    ;
 229
 230 1;