| 1 | .\" Automatically generated by Pod::Man v1.34, Pod::Parser v1.13 |
| 2 | .\" |
| 3 | .\" Standard preamble: |
| 4 | .\" ======================================================================== |
| 5 | .de Sh \" Subsection heading |
| 6 | .br |
| 7 | .if t .Sp |
| 8 | .ne 5 |
| 9 | .PP |
| 10 | \fB\\$1\fR |
| 11 | .PP |
| 12 | .. |
| 13 | .de Sp \" Vertical space (when we can't use .PP) |
| 14 | .if t .sp .5v |
| 15 | .if n .sp |
| 16 | .. |
| 17 | .de Vb \" Begin verbatim text |
| 18 | .ft CW |
| 19 | .nf |
| 20 | .ne \\$1 |
| 21 | .. |
| 22 | .de Ve \" End verbatim text |
| 23 | .ft R |
| 24 | .fi |
| 25 | .. |
| 26 | .\" Set up some character translations and predefined strings. \*(-- will |
| 27 | .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left |
| 28 | .\" double quote, and \*(R" will give a right double quote. | will give a |
| 29 | .\" real vertical bar. \*(C+ will give a nicer C++. Capital omega is used to |
| 30 | .\" do unbreakable dashes and therefore won't be available. \*(C` and \*(C' |
| 31 | .\" expand to `' in nroff, nothing in troff, for use with C<>. |
| 32 | .tr \(*W-|\(bv\*(Tr |
| 33 | .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' |
| 34 | .ie n \{\ |
| 35 | . ds -- \(*W- |
| 36 | . ds PI pi |
| 37 | . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch |
| 38 | . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch |
| 39 | . ds L" "" |
| 40 | . ds R" "" |
| 41 | . ds C` "" |
| 42 | . ds C' "" |
| 43 | 'br\} |
| 44 | .el\{\ |
| 45 | . ds -- \|\(em\| |
| 46 | . ds PI \(*p |
| 47 | . ds L" `` |
| 48 | . ds R" '' |
| 49 | 'br\} |
| 50 | .\" |
| 51 | .\" If the F register is turned on, we'll generate index entries on stderr for |
| 52 | .\" titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and index |
| 53 | .\" entries marked with X<> in POD. Of course, you'll have to process the |
| 54 | .\" output yourself in some meaningful fashion. |
| 55 | .if \nF \{\ |
| 56 | . de IX |
| 57 | . tm Index:\\$1\t\\n%\t"\\$2" |
| 58 | .. |
| 59 | . nr % 0 |
| 60 | . rr F |
| 61 | .\} |
| 62 | .\" |
| 63 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
| 64 | .\" way too many mistakes in technical documents. |
| 65 | .hy 0 |
| 66 | .if n .na |
| 67 | .\" |
| 68 | .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). |
| 69 | .\" Fear. Run. Save yourself. No user-serviceable parts. |
| 70 | . \" fudge factors for nroff and troff |
| 71 | .if n \{\ |
| 72 | . ds #H 0 |
| 73 | . ds #V .8m |
| 74 | . ds #F .3m |
| 75 | . ds #[ \f1 |
| 76 | . ds #] \fP |
| 77 | .\} |
| 78 | .if t \{\ |
| 79 | . ds #H ((1u-(\\\\n(.fu%2u))*.13m) |
| 80 | . ds #V .6m |
| 81 | . ds #F 0 |
| 82 | . ds #[ \& |
| 83 | . ds #] \& |
| 84 | .\} |
| 85 | . \" simple accents for nroff and troff |
| 86 | .if n \{\ |
| 87 | . ds ' \& |
| 88 | . ds ` \& |
| 89 | . ds ^ \& |
| 90 | . ds , \& |
| 91 | . ds ~ ~ |
| 92 | . ds / |
| 93 | .\} |
| 94 | .if t \{\ |
| 95 | . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" |
| 96 | . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' |
| 97 | . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' |
| 98 | . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' |
| 99 | . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' |
| 100 | . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' |
| 101 | .\} |
| 102 | . \" troff and (daisy-wheel) nroff accents |
| 103 | .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' |
| 104 | .ds 8 \h'\*(#H'\(*b\h'-\*(#H' |
| 105 | .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] |
| 106 | .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' |
| 107 | .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' |
| 108 | .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] |
| 109 | .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] |
| 110 | .ds ae a\h'-(\w'a'u*4/10)'e |
| 111 | .ds Ae A\h'-(\w'A'u*4/10)'E |
| 112 | . \" corrections for vroff |
| 113 | .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' |
| 114 | .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' |
| 115 | . \" for low resolution devices (crt and lpr) |
| 116 | .if \n(.H>23 .if \n(.V>19 \ |
| 117 | \{\ |
| 118 | . ds : e |
| 119 | . ds 8 ss |
| 120 | . ds o a |
| 121 | . ds d- d\h'-1'\(ga |
| 122 | . ds D- D\h'-1'\(hy |
| 123 | . ds th \o'bp' |
| 124 | . ds Th \o'LP' |
| 125 | . ds ae ae |
| 126 | . ds Ae AE |
| 127 | .\} |
| 128 | .rm #[ #] #H #V #F C |
| 129 | .\" ======================================================================== |
| 130 | .\" |
| 131 | .IX Title "strict 3" |
| 132 | .TH strict 3 "2002-06-01" "perl v5.8.0" "Perl Programmers Reference Guide" |
| 133 | .SH "NAME" |
| 134 | strict \- Perl pragma to restrict unsafe constructs |
| 135 | .SH "SYNOPSIS" |
| 136 | .IX Header "SYNOPSIS" |
| 137 | .Vb 1 |
| 138 | \& use strict; |
| 139 | .Ve |
| 140 | .PP |
| 141 | .Vb 3 |
| 142 | \& use strict "vars"; |
| 143 | \& use strict "refs"; |
| 144 | \& use strict "subs"; |
| 145 | .Ve |
| 146 | .PP |
| 147 | .Vb 2 |
| 148 | \& use strict; |
| 149 | \& no strict "vars"; |
| 150 | .Ve |
| 151 | .SH "DESCRIPTION" |
| 152 | .IX Header "DESCRIPTION" |
| 153 | If no import list is supplied, all possible restrictions are assumed. |
| 154 | (This is the safest mode to operate in, but is sometimes too strict for |
| 155 | casual programming.) Currently, there are three possible things to be |
| 156 | strict about: \*(L"subs\*(R", \*(L"vars\*(R", and \*(L"refs\*(R". |
| 157 | .ie n .IP """strict refs""" 6 |
| 158 | .el .IP "\f(CWstrict refs\fR" 6 |
| 159 | .IX Item "strict refs" |
| 160 | This generates a runtime error if you |
| 161 | use symbolic references (see perlref). |
| 162 | .Sp |
| 163 | .Vb 7 |
| 164 | \& use strict 'refs'; |
| 165 | \& $ref = \e$foo; |
| 166 | \& print $$ref; # ok |
| 167 | \& $ref = "foo"; |
| 168 | \& print $$ref; # runtime error; normally ok |
| 169 | \& $file = "STDOUT"; |
| 170 | \& print $file "Hi!"; # error; note: no comma after $file |
| 171 | .Ve |
| 172 | .Sp |
| 173 | There is one exception to this rule: |
| 174 | .Sp |
| 175 | .Vb 2 |
| 176 | \& $bar = \e&{'foo'}; |
| 177 | \& &$bar; |
| 178 | .Ve |
| 179 | .Sp |
| 180 | is allowed so that \f(CW\*(C`goto &$AUTOLOAD\*(C'\fR would not break under stricture. |
| 181 | .ie n .IP """strict vars""" 6 |
| 182 | .el .IP "\f(CWstrict vars\fR" 6 |
| 183 | .IX Item "strict vars" |
| 184 | This generates a compile-time error if you access a variable that wasn't |
| 185 | declared via \*(L"our\*(R" or \f(CW\*(C`use vars\*(C'\fR, |
| 186 | localized via \f(CW\*(C`my()\*(C'\fR, or wasn't fully qualified. Because this is to avoid |
| 187 | variable suicide problems and subtle dynamic scoping issues, a merely |
| 188 | \&\fIlocal()\fR variable isn't good enough. See \*(L"my\*(R" in perlfunc and |
| 189 | \&\*(L"local\*(R" in perlfunc. |
| 190 | .Sp |
| 191 | .Vb 4 |
| 192 | \& use strict 'vars'; |
| 193 | \& $X::foo = 1; # ok, fully qualified |
| 194 | \& my $foo = 10; # ok, my() var |
| 195 | \& local $foo = 9; # blows up |
| 196 | .Ve |
| 197 | .Sp |
| 198 | .Vb 3 |
| 199 | \& package Cinna; |
| 200 | \& our $bar; # Declares $bar in current package |
| 201 | \& $bar = 'HgS'; # ok, global declared via pragma |
| 202 | .Ve |
| 203 | .Sp |
| 204 | The \fIlocal()\fR generated a compile-time error because you just touched a global |
| 205 | name without fully qualifying it. |
| 206 | .Sp |
| 207 | Because of their special use by \fIsort()\fR, the variables \f(CW$a\fR and \f(CW$b\fR are |
| 208 | exempted from this check. |
| 209 | .ie n .IP """strict subs""" 6 |
| 210 | .el .IP "\f(CWstrict subs\fR" 6 |
| 211 | .IX Item "strict subs" |
| 212 | This disables the poetry optimization, generating a compile-time error if |
| 213 | you try to use a bareword identifier that's not a subroutine, unless it |
| 214 | appears in curly braces or on the left hand side of the "=>" symbol. |
| 215 | .Sp |
| 216 | .Vb 4 |
| 217 | \& use strict 'subs'; |
| 218 | \& $SIG{PIPE} = Plumber; # blows up |
| 219 | \& $SIG{PIPE} = "Plumber"; # just fine: bareword in curlies always ok |
| 220 | \& $SIG{PIPE} = \e&Plumber; # preferred form |
| 221 | .Ve |
| 222 | .PP |
| 223 | See \*(L"Pragmatic Modules\*(R" in perlmodlib. |