source: vendor/perl/5.8.8/Changes5.000@ 3181

Last change on this file since 3181 was 3181, checked in by bird, 18 years ago

perl 5.8.8
File size: 7.5 KB
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1-------------
2Version 5.000
3-------------
4
5New things
6----------
7 The -w switch is much more informative.
8
9 References. See t/op/ref.t for examples. All entities in Perl 5 are
10 reference counted so that it knows when each item should be destroyed.
11
12 Objects. See t/op/ref.t for examples.
13
14 => is now a synonym for comma. This is useful as documentation for
15 arguments that come in pairs, such as initializers for associative arrays,
16 or named arguments to a subroutine.
17
18 All functions have been turned into list operators or unary operators,
19 meaning the parens are optional. Even subroutines may be called as
20 list operators if they've already been declared.
21
22 More embeddible. See main.c and embed_h.sh. Multiple interpreters
23 in the same process are supported (though not with interleaved
24 execution yet).
25
26 The interpreter is now flattened out. Compare Perl 4's eval.c with
27 the perl 5's pp.c. Compare Perl 4's 900 line interpreter loop in cmd.c
28 with Perl 5's 1 line interpreter loop in run.c. Eventually we'll make
29 everything non-blocking so we can interface nicely with a scheduler.
30
31 eval is now treated more like a subroutine call. Among other things,
32 this means you can return from it.
33
34 Format value lists may be spread over multiple lines by enclosing in
35 a do {} block.
36
37 You may now define BEGIN and END subroutines for each package. The BEGIN
38 subroutine executes the moment it's parsed. The END subroutine executes
39 just before exiting.
40
41 Flags on the #! line are interpreted even if the script wasn't
42 executed directly. (And even if the script was located by "perl -x"!)
43
44 The ?: operator is now legal as an lvalue.
45
46 List context now propagates to the right side of && and ||, as well
47 as the 2nd and 3rd arguments to ?:.
48
49 The "defined" function can now take a general expression.
50
51 Lexical scoping available via "my". eval can see the current lexical
52 variables.
53
54 The preferred package delimiter is now :: rather than '.
55
56 tie/untie are now preferred to dbmopen/dbmclose. Multiple DBM
57 implementations are allowed in the same executable, so you can
58 write scripts to interchange data among different formats.
59
60 New "and" and "or" operators work just like && and || but with
61 a precedence lower than comma, so they work better with list operators.
62
63 New functions include: abs(), chr(), uc(), ucfirst(), lc(), lcfirst(),
64 chomp(), glob()
65
66 require with a number checks to see that the version of Perl that is
67 currently running is at least that number.
68
69 Dynamic loading of external modules is now supported.
70
71 There is a new quote form qw//, which is equivalent to split(' ', q//).
72
73 Assignment of a reference to a glob value now just replaces the
74 single element of the glob corresponding to the reference type:
75 *foo = \$bar, *foo = \&bletch;
76
77 Filehandle methods are now supported:
78 output_autoflush STDOUT 1;
79
80 There is now an "English" module that provides human readable translations
81 for cryptic variable names.
82
83 Autoload stubs can now call the replacement subroutine with goto &realsub.
84
85 Subroutines can be defined lazily in any package by declaring an AUTOLOAD
86 routine, which will be called if a non-existent subroutine is called in
87 that package.
88
89 Several previously added features have been subsumed under the new
90 keywords "use" and "no". Saying "use Module LIST" is short for
91 BEGIN { require Module; import Module LIST; }
92 The "no" keyword is identical except that it calls "unimport" instead.
93 The earlier pragma mechanism now uses this mechanism, and two new
94 modules have been added to the library to implement "use integer"
95 and variations of "use strict vars, refs, subs".
96
97 Variables may now be interpolated literally into a pattern by prefixing
98 them with \Q, which works just like \U, but backwhacks non-alphanumerics
99 instead. There is also a corresponding quotemeta function.
100
101 Any quantifier in a regular expression may now be followed by a ? to
102 indicate that the pattern is supposed to match as little as possible.
103
104 Pattern matches may now be followed by an m or s modifier to explicitly
105 request multiline or singleline semantics. An s modifier makes . match
106 newline.
107
108 Patterns may now contain \A to match only at the beginning of the string,
109 and \Z to match only at the end. These differ from ^ and $ in that
110 they ignore multiline semantics. In addition, \G matches where the
111 last interation of m//g or s///g left off.
112
113 Non-backreference-producing parens of various sorts may now be
114 indicated by placing a ? directly after the opening parenthesis,
115 followed by a character that indicates the purpose of the parens.
116 An :, for instance, indicates simple grouping. (?:a|b|c) will
117 match any of a, b or c without producing a backreference. It does
118 "eat" the input. There are also assertions which do not eat the
119 input but do lookahead for you. (?=stuff) indicates that the next
120 thing must be "stuff". (?!nonsense) indicates that the next thing
121 must not be "nonsense".
122
123 The negation operator now treats non-numeric strings specially.
124 A -"text" is turned into "-text", so that -bareword is the same
125 as "-bareword". If the string already begins with a + or -, it
126 is flipped to the other sign.
127
128Incompatibilities
129-----------------
130 @ now always interpolates an array in double-quotish strings. Some programs
131 may now need to use backslash to protect any @ that shouldn't interpolate.
132
133 Ordinary variables starting with underscore are no longer forced into
134 package main.
135
136 s'$lhs'$rhs' now does no interpolation on either side. It used to
137 interplolate $lhs but not $rhs.
138
139 The second and third arguments of splice are now evaluated in scalar
140 context (like the book says) rather than list context.
141
142 Saying "shift @foo + 20" is now a semantic error because of precedence.
143
144 "open FOO || die" is now incorrect. You need parens around the filehandle.
145
146 The elements of argument lists for formats are now evaluated in list
147 context. This means you can interpolate list values now.
148
149 You can't do a goto into a block that is optimized away. Darn.
150
151 It is no longer syntactically legal to use whitespace as the name
152 of a variable, or as a delimiter for any kind of quote construct.
153
154 Some error messages will be different.
155
156 The caller function now returns a false value in a scalar context if there
157 is no caller. This lets library files determine if they're being required.
158
159 m//g now attaches its state to the searched string rather than the
160 regular expression.
161
162 "reverse" is no longer allowed as the name of a sort subroutine.
163
164 taintperl is no longer a separate executable. There is now a -T
165 switch to turn on tainting when it isn't turned on automatically.
166
167 Symbols starting with _ are no longer forced into package main, except
168 for $_ itself (and @_, etc.).
169
170 Double-quoted strings may no longer end with an unescaped $ or @.
171
172 Negative array subscripts now count from the end of the array.
173
174 The comma operator in a scalar context is now guaranteed to give a
175 scalar context to its arguments.
176
177 The ** operator now binds more tightly than unary minus.
178
179 Setting $#array lower now discards array elements so that destructors
180 work reasonably.
181
182 delete is not guaranteed to return the old value for tied arrays,
183 since this capability may be onerous for some modules to implement.
184
185 Attempts to set $1 through $9 now result in a run-time error.
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