| 1 | -------------
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| 2 | Version 5.000
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| 3 | -------------
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| 4 |
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| 5 | New things
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| 6 | ----------
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| 7 | The -w switch is much more informative.
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| 8 |
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| 9 | References. See t/op/ref.t for examples. All entities in Perl 5 are
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| 10 | reference counted so that it knows when each item should be destroyed.
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| 11 |
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| 12 | Objects. See t/op/ref.t for examples.
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| 13 |
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| 14 | => is now a synonym for comma. This is useful as documentation for
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| 15 | arguments that come in pairs, such as initializers for associative arrays,
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| 16 | or named arguments to a subroutine.
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| 17 |
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| 18 | All functions have been turned into list operators or unary operators,
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| 19 | meaning the parens are optional. Even subroutines may be called as
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| 20 | list operators if they've already been declared.
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| 21 |
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| 22 | More embeddible. See main.c and embed_h.sh. Multiple interpreters
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| 23 | in the same process are supported (though not with interleaved
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| 24 | execution yet).
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| 25 |
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| 26 | The interpreter is now flattened out. Compare Perl 4's eval.c with
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| 27 | the perl 5's pp.c. Compare Perl 4's 900 line interpreter loop in cmd.c
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| 28 | with Perl 5's 1 line interpreter loop in run.c. Eventually we'll make
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| 29 | everything non-blocking so we can interface nicely with a scheduler.
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| 30 |
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| 31 | eval is now treated more like a subroutine call. Among other things,
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| 32 | this means you can return from it.
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| 33 |
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| 34 | Format value lists may be spread over multiple lines by enclosing in
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| 35 | a do {} block.
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| 36 |
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| 37 | You may now define BEGIN and END subroutines for each package. The BEGIN
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| 38 | subroutine executes the moment it's parsed. The END subroutine executes
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| 39 | just before exiting.
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| 40 |
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| 41 | Flags on the #! line are interpreted even if the script wasn't
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| 42 | executed directly. (And even if the script was located by "perl -x"!)
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| 43 |
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| 44 | The ?: operator is now legal as an lvalue.
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| 45 |
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| 46 | List context now propagates to the right side of && and ||, as well
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| 47 | as the 2nd and 3rd arguments to ?:.
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| 48 |
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| 49 | The "defined" function can now take a general expression.
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| 50 |
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| 51 | Lexical scoping available via "my". eval can see the current lexical
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| 52 | variables.
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| 53 |
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| 54 | The preferred package delimiter is now :: rather than '.
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| 55 |
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| 56 | tie/untie are now preferred to dbmopen/dbmclose. Multiple DBM
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| 57 | implementations are allowed in the same executable, so you can
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| 58 | write scripts to interchange data among different formats.
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| 59 |
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| 60 | New "and" and "or" operators work just like && and || but with
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| 61 | a precedence lower than comma, so they work better with list operators.
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| 62 |
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| 63 | New functions include: abs(), chr(), uc(), ucfirst(), lc(), lcfirst(),
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| 64 | chomp(), glob()
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| 65 |
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| 66 | require with a number checks to see that the version of Perl that is
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| 67 | currently running is at least that number.
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| 68 |
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| 69 | Dynamic loading of external modules is now supported.
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| 70 |
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| 71 | There is a new quote form qw//, which is equivalent to split(' ', q//).
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| 72 |
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| 73 | Assignment of a reference to a glob value now just replaces the
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| 74 | single element of the glob corresponding to the reference type:
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| 75 | *foo = \$bar, *foo = \&bletch;
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| 76 |
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| 77 | Filehandle methods are now supported:
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| 78 | output_autoflush STDOUT 1;
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| 79 |
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| 80 | There is now an "English" module that provides human readable translations
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| 81 | for cryptic variable names.
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| 82 |
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| 83 | Autoload stubs can now call the replacement subroutine with goto &realsub.
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| 84 |
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| 85 | Subroutines can be defined lazily in any package by declaring an AUTOLOAD
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| 86 | routine, which will be called if a non-existent subroutine is called in
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| 87 | that package.
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| 88 |
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| 89 | Several previously added features have been subsumed under the new
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| 90 | keywords "use" and "no". Saying "use Module LIST" is short for
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| 91 | BEGIN { require Module; import Module LIST; }
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| 92 | The "no" keyword is identical except that it calls "unimport" instead.
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| 93 | The earlier pragma mechanism now uses this mechanism, and two new
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| 94 | modules have been added to the library to implement "use integer"
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| 95 | and variations of "use strict vars, refs, subs".
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| 96 |
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| 97 | Variables may now be interpolated literally into a pattern by prefixing
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| 98 | them with \Q, which works just like \U, but backwhacks non-alphanumerics
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| 99 | instead. There is also a corresponding quotemeta function.
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| 100 |
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| 101 | Any quantifier in a regular expression may now be followed by a ? to
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| 102 | indicate that the pattern is supposed to match as little as possible.
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| 103 |
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| 104 | Pattern matches may now be followed by an m or s modifier to explicitly
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| 105 | request multiline or singleline semantics. An s modifier makes . match
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| 106 | newline.
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| 107 |
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| 108 | Patterns may now contain \A to match only at the beginning of the string,
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| 109 | and \Z to match only at the end. These differ from ^ and $ in that
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| 110 | they ignore multiline semantics. In addition, \G matches where the
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| 111 | last interation of m//g or s///g left off.
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| 112 |
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