Support for strings represented as a vector of ordinals
Literals of the form C<v1.2.3.4> are now parsed as a string composed
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}">. The leading
C<v> may be omitted if there are more than two ordinals, so C<1.2.3> is
parsed the same as C<v1.2.3>.
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<$^V> magic variable (which contains
the perl version as a string), such literals can be used as a readable way
to check if you're running a particular version of Perl:
# this will parse in older versions of Perl also
if ($^V and $^V gt v5.6.0) {
# new features supported
}
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
Alternatively, the C<v> may be omitted if there is more than one dot:
require 5.6.0;
use 5.6.0;
Also, C<sprintf> and C<printf> support the Perl-specific format flag C<%v>
to print ordinals of characters in arbitrary strings:
printf "v%vd", $^V; # prints current version, such as "v5.5.650"
printf "%*vX", ":", $addr; # formats IPv6 address
printf "%*vb", " ", $bits; # displays bitstring
See L<perldata/"Scalar value constructors"> for additional information.
=head2 Improved Perl version numbering system
Beginning with Perl version 5.6.0, 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 v5.6.0 will be numbered v5.7.x,
beginning with v5.7.0, and the next major production release following
v5.6.0 will be v5.8.0.
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 v5.6.0 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 should be read as being
equivalent to a floating point value of 5.006_001 in the older format,
stored in C<$]>).
