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Diffstat (limited to 'pod/perldelta.pod')
| -rw-r--r-- | pod/perldelta.pod | 108 |
1 files changed, 63 insertions, 45 deletions
diff --git a/pod/perldelta.pod b/pod/perldelta.pod index 2bedcdb6c9..746c242288 100644 --- a/pod/perldelta.pod +++ b/pod/perldelta.pod @@ -57,6 +57,33 @@ cases remains unchanged: See L<perldata>. +=head2 Perl's version numbering has changed + +Beginning with Perl version 5.6, the version number convention has been +changed to a "dotted integer" scheme that is more commonly found in open +source projects. + +Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. +The next development series following v5.6 will be numbered v5.7.x, +beginning with v5.7.0, and the next major production release following +v5.6 will be v5.8. + +The English module now sets $PERL_VERSION to $^V (a string value) rather +than C<$]> (a numeric value). (This is a potential incompatibility. +Send us a report via perlbug if you are affected by this.) + +The v1.2.3 syntax is also now legal in Perl. +See L<Support for strings represented as a vector of ordinals> for more on that. + +To cope with the new versioning system's use of at least three significant +digits for each version component, the method used for incrementing the +subversion number has also changed slightly. We assume that versions older +than v5.6 have been incrementing the subversion component in multiples of +10. Versions after v5.6.0 will increment them by 1. Thus, using the new +notation, 5.005_03 is the same as v5.5.30, and the first maintenance +version following v5.6.0 will be v5.6.1, which amounts to a floating point +value of 5.006_001). + =item Possibly changed pseudo-random number generator In 5.005_0x and earlier, perl's rand() function used the C library @@ -286,29 +313,6 @@ create new threads from Perl (i.e., C<use Thread;> will not work with interpreter threads). C<use Thread;> continues to be available when you ask for -Duse5005threads, bugs and all. -=head2 Perl's version numbering has changed - -Beginning with Perl version 5.6, the version number convention has been -changed to a "dotted tuple" scheme that is more commonly found in open -source projects. - -Maintenance versions of v5.6.0 will be released as v5.6.1, v5.6.2 etc. -The next development series following v5.6 will be numbered v5.7.x, -beginning with v5.7.0, and the next major production release following -v5.6 will be v5.8. - -The v1.2.3 syntax is also now legal in Perl. See L<Support for version tuples> -for more on that. - -To cope with the new versioning system's use of at least three significant -digits for each version component, the method used for incrementing the -subversion number has also changed slightly. We assume that versions older -than v5.6 have been incrementing the subversion component in multiples of -10. Versions after v5.6 will increment them by 1. Thus, using the new -notation, 5.005_03 is the same as v5.5.30, and the first maintenance -version following v5.6 will be v5.6.1, which amounts to a floating point -value of 5.006_001). - =head2 New Configure flags The following new flags may be enabled on the Configure command line @@ -455,36 +459,42 @@ mostly useful as an alternative to the C<vars> pragma, but also provides the opportunity to introduce typing and other attributes for such variables. See L<perlfunc/our>. -=head2 Support for version tuples +=head2 Support for strings represented as a vector of ordinals -Literals of the form v1.2.3.4 are now parsed as the utf8 string -C<"\x{1}\x{2}\x{3}\x{4}">. This allows comparing version numbers using -regular string comparison operators C<eq>, C<ne>, C<lt>, C<gt> etc. +Literals of the form v1.2.3.4 are now parsed as a string comprised of +of characters with the specified ordinals. This is an alternative, more +readable way to construct (possibly unicode) strings instead of +interpolating characters, as in C<"\x{1}\x{2}\x{3}\x{4}">. -These "dotted tuples" are dual-valued. They are both strings of utf8 -characters, and floating point numbers. Thus v1.2.3.4 has the string -value C<"\x{1}\x{2}\x{3}\x{4}"> and the numeric value 1.002_003_004. -As another example, v5.5.640 has the string value C<"\x{5}\x{5}\x{280}"> -(remember 280 hexadecimal is 640 decimal) and the numeric value -5.005_64. +Strings written in this form are also useful to represent version "numbers". +It is easy to compare such version "numbers" (which are really just plain +strings) using any of the usual string comparison operators C<eq>, C<ne>, +C<lt>, C<gt>, etc., or perform bitwise string operations on them using C<|>, +C<&>, etc. In conjunction with the new C<$^V> magic variable (which contains -the perl version in this format), such literals can be used to -check if you're running a particular version of Perl. +the perl version as a string), such literals can be used as a readable way +to check if you're running a particular version of Perl: + # this will parse in older versions of Perl also if ($^V and $^V gt v5.5.640) { - # new style version numbers are supported + # new features supported } -C<require> and C<use> also support such literals: +C<require> and C<use> also have some special magic to support such literals. +They will be interpreted as a version rather than as a module name: + + require v5.6.0; # croak if $^V lt v5.6.0 + use v5.6.0; # same, but croaks at compile-time - require v5.6.0; # croak if $^V lt v5.6.0 - use v5.6.0; # same, but croaks at compile-time +Also, C<sprintf> and C<printf> support the Perl-specific format flag C<%v> +to print ordinals of characters in arbitrary strings: -C<sprintf> and C<printf> support the Perl-specific format type C<%v> -to print arbitrary strings as dotted tuples. + printf "v%vd", $^V; # prints current version, such as "v5.5.650" + printf "%*vX", ":", $addr; # formats IPv6 address + printf "%*vb", "", $bits; # displays bitstring as contiguous 0's and 1's - printf "v%v", $^V; # prints current version, such as "v5.5.650" +See L<perlop/"Strings of Character"> for additional information. =head2 Weak references @@ -851,9 +861,12 @@ only during normal running are warranted. See L<perlvar>. =head2 New variable $^V contains Perl version in v5.6.0 format -C<$^V> contains the Perl version number as a version tuple that -can be used in string or numeric comparisons. See -C<Support for version tuples> for an example. +C<$^V> contains the Perl version number as a string comprised of +characters whose ordinals match the version numbers, so that it may +be used in string comparisons. + +See C<Support for strings represented as a vector of ordinals> for an +example. =head2 Optional Y2K warnings @@ -1388,6 +1401,11 @@ For other details, see L<Benchmark>. The Devel::Peek module provides access to the internal representation of Perl variables and data. It is a data debugging tool for the XS programmer. +=item English + +$PERL_VERSION now stands for C<$^V> (a string value) rather than for C<$]> +(a numeric value). + =item ExtUtils::MakeMaker change#4135, also needs docs in module pod |