man Perl::Version (3): Parse and manipulate Perl version strings

VERSION

This document describes Perl::Version version 1.013

SYNOPSIS

use Perl::Version;
# Init from string
my $version = Perl::Version->new( '1.2.3' );
# Stringification preserves original format
print "$version\n"; # prints '1.2.3'
# Normalised
print $version->normal, "\n"; # prints 'v1.2.3'
# Numified
print $version->numify, "\n"; # prints '1.002003'
# Explicitly stringified
print $version->stringify, "\n"; # prints '1.2.3'
# Increment the subversion (the third component)
$version->inc_subversion;
# Stringification returns the updated version formatted
# as the original was
print "$version\n"; # prints '1.2.4'
# Normalised
print $version->normal, "\n"; # prints 'v1.2.4'
# Numified
print $version->numify, "\n"; # prints '1.002004'
# Refer to subversion component by position ( zero based )
$version->increment( 2 );
print "$version\n"; # prints '1.2.5'
# Increment the version (second component) which sets all
# components to the right of it to zero.
$version->inc_version;
print "$version\n"; # prints '1.3.0'
# Increment the revision (main version number)
$version->inc_revision;
print "$version\n"; # prints '2.0.0'
# Increment the alpha number
$version->inc_alpha;
print "$version\n"; # prints '2.0.0_001'

DESCRIPTION

Perl::Version provides a simple interface for parsing, manipulating and formatting Perl version strings.

Unlike version.pm (which concentrates on parsing and comparing version strings) Perl::Version is designed for cases where you'd like to parse a version, modify it and get back the modified version formatted like the original.

For example:

    my $version = Perl::Version->new( '1.2.3' );
    $version->inc_version;
    print "$version\n";

prints

    1.3.0

whereas

    my $version = Perl::Version->new( 'v1.02.03' );
    $version->inc_version;
    print "$version\n";

prints

    v1.03.00

Both are representations of the same version and they'd compare equal but their formatting is different.

Perl::Version tries hard to guess and recreate the format of the original version and in most cases it succeeds. In rare cases the formatting is ambiguous. Consider

    1.10.03

Do you suppose that second component '10' is zero padded like the third component? Perl::Version will assume that it is:

    my $version = Perl::Version->new( '1.10.03' );
    $version->inc_revision;
    print "$version\n";

will print

    2.00.00

If all of the components after the first are the same length (two characters in this case) and any of them begins with a zero Perl::Version will assume that they're all zero padded to the same length.

The first component and any alpha suffix are handled separately. In each case if either of them starts with a zero they will be zero padded to the same length when stringifying the version.

Version Formats

Perl::Version supports a few different version string formats.

1, 1.2

Versions that look like a number. If you pass a numeric value its string equivalent will be parsed:

    my $version = Perl::Version->new( 1.2 );
    print "$version\n";

prints

1.2

In fact there is no special treatment for versions that resemble decimal numbers. This is worthy of comment only because it differs from version.pm which treats actual numbers used as versions as a special case and performs various transformations on the stored version.

1.2.3, 1.2.3.4

Simple versions with three or more components.

v1.2.3

Versions with a leading 'v'.

5.008006

Fielded numeric versions. You'll likely have seen this in relation to versions of Perl itself. If a version string has a single decimal point and the part after the point is three more more digits long, components are extracted from each group of three digits in the fractional part.

For example

    my $version = Perl::Version->new( 1.002003004005006 );
    print $version->normal;

prints

    v1.2.3.4.5.6

vstring

Perls later than 5.8.1 support vstring format. A vstring looks like a number with more than one decimal point and (optionally) a leading 'v'. The 'v' is mandatory for vstrings containing fewer than two decimal points.

Perl::Version will successfully parse vstrings

    my $version = Perl::Version->new( v1.2 );
    print "$version\n";

prints

    v1.2

Note that stringifying a Perl::Version constructed from a vstring will result in a regular string. Because it has no way of knowing whether the vstring constant had a 'v' prefix it always generates one when stringifying back to a version string.

CVS version

A common idiom for users of CVS is to use keyword replacement to generate a version automatically like this:

    $VERSION = version->new( qw$Revision: 2.7 $ );

Perl::Version does the right thing with such versions so that

    my $version = Perl::Version->new( qw$Revision: 2.7 $ );
    $version->inc_revision;
    print "$version\n";

prints

    Revision: 3.0

Real Numbers

Real numbers are stringified before parsing. This has two implications: trailing zeros after the decimal point will be lost and any underscore characters in the number are discarded.

Perl allows underscores anywhere in numeric constants as an aid to formatting. These are discarded when Perl converts the number into its internal format. This means that

    # Numeric version
    print Perl::Version->new( 1.001_001 )->stringify;

prints

    1.001001

but

    # String version
    print Perl::Version->new( '1.001_001' )->stringify;

prints

    1.001_001

as expected.

In general you should probably avoid versions expressed either as decimal numbers or vstrings. The safest option is to pass a regular string to Perl::Version->new().

Alpha Versions

By convention if a version string has suffix that consists of an underscore followed by one or more digits it represents an alpha or developer release. CPAN treats modules with such version strings specially to reflect their alpha status.

This alpha notation is one reason why using decimal numbers as versions is a bad idea. Underscore is a valid character in numeric constants which is discarded by Perl when a program's source is parsed so any intended alpha suffix will become part of the version number.

To be considered alpha a version must have a non-zero alpha component like this

    3.0.4_001

Generally the alpha component will be formatted with leading zeros but this is not a requirement.

Component Naming

A version number consists of a series of components. By Perl convention the first three components are named 'revision', 'version' and 'subversion':

    $ perl -V
    Summary of my perl5 (revision 5 version 8 subversion 6) configuration:
    
    (etc)

Perl::Version follows that convention. Any component may be accessed by passing a number from 0 to N-1 to the component or increment but for convenience the first three components are aliased as revision, version and subversion.

    $version->increment( 0 );

is the same as

    $version->inc_revision;

and

    my $subv = $version->subversion;

is the same as

    my $subv = $version->component( 2 );

The alpha component is named 'alpha'.

Comparison with version.pm

If you're familiar with version.pm you'll notice that there's a certain amount of overlap between what it does and this module. I originally created this module as a mutable subclass of version.pm but the requirement to be able to reformat a modified version to match the formatting of the original didn't sit well with version.pm's internals.

As a result this module is not dependent or based on version.pm.

INTERFACE

"new"

Create a new Perl::Version by parsing a version string. As discussed above a number of different version formats are supported. Along with the value of the version formatting information is captured so that the version can be modified and the updated value retrieved in the same format as the original.

    my @version = (
        '1.3.0',    'v1.03.00',     '1.10.03', '2.00.00',
        '1.2',      'v1.2.3.4.5.6', 'v1.2',    'Revision: 3.0',
        '1.001001', '1.001_001',    '3.0.4_001',
    );
    for my $v ( @version ) {
        my $version = Perl::Version->new( $v );
        $version->inc_version;
        print "$version\n";
    }

prints

    1.4.0
    v1.04.00
    1.11.00
    2.01.00
    1.3
    v1.3.0.0.0.0
    v1.3
    Revision: 3.1
    1.002000
    1.002
    3.1.0

In each case the incremented version is formatted in the same way as the original.

If no arguments are passed an empty version intialised to 'v0' will be constructed.

In order to support CVS version syntax

    my $version = Perl::Version->new( qw$Revision: 2.7 $ );

"new" may be passed an array in which case it concatenates all of its arguments with spaces before parsing the result.

If the string can't be parsed as a version "new" will croak with a suitable error. See DIAGNOSTICS for more information.

Accessors

"component"

Set or get one of the components of a version.

    # Set the subversion
    $version->component( 2, 17 );
    
    # Get the revision
    my $rev = $version->component( 0 );

Instead of a component number you may pass a name: 'revision', 'version', 'subversion' or 'alpha':

    my $rev = $version->component( 'revision' );

"components"

Get or set all of the components of a version.

    # Set the number of components
    $version->components( 4 );
    
    # Get the number of components
    my $parts = $version->components;
    
    # Get the individual components as an array
    my @parts = $version->components;
    
    # Set the components from an array
    $version->components( [ 5, 9, 2 ] );

Hmm. That's a lot of interface for one subroutine. Sorry about that.

"revision"

Alias for component( 0 ). Gets or sets the revision component.

"version"

Alias for component( 1 ). Gets or sets the version component.

"subversion"

Alias for component( 2 ). Gets or sets the subversion component.

"alpha"

Get or set the alpha component of a version. Returns 0 for versions with no alpha.

    # Set alpha
    $version->alpha( 12 );
    
    # Get alpha
    my $alp = $version->alpha;

"is_alpha"

Return true if a version has a non-zero alpha component.

"set"

Set the version to match another version preserving the formatting of this version.

    $version->set( $other_version );

You may also set the version from a literal string:

    $version->set( '1.2.3' );

The version will be updated to the value of the version string but will retain its current formatting.

Incrementing

"increment"

Increment a component of a version.

    my $version = Perl::Version->new( '3.1.4' );
    $version->increment( 1 );
    print "$version\n";

prints

    3.2.0

Components to the right of the incremented component will be set to zero as will any alpha component.

As an alternative to passing a component number one of the predefined component names 'revision', 'version', 'subversion' or 'alpha' may be passed.

"inc_alpha"

Increment a version's alpha component.

"inc_revision"

Increment a version's revision component.

"inc_subversion"

Increment a version's subversion component.

"inc_version"

Increment a version's version component.

Formatting

"normal"

Return a normalised representation of a version.

    my $version = Perl::Version->new( '5.008007_01' );
    print $version->normal, "\n";

prints

    v5.8.7_001

"numify"

Return a numeric representation of a version. The numeric form is most frequently used for versions of Perl itself.

    my $version = Perl::Version->new( '5.8.7_1' );
    print $version->normal, "\n";

prints

    5.008007_001

"stringify"

Return the version formatted as closely as possible to the version from which it was initialised.

    my $version = Perl::Version->new( '5.008007_01' );
    $version->inc_alpha;
    print $version->stringify, "\n";

prints

    5.008007_02

and

    my $version = Perl::Version->new( '5.8.7_1' );
    $version->inc_alpha;
    print $version->stringify, "\n";

prints

    5.8.7_2

Comparison

"vcmp"

Perform 'spaceship' comparison between two version and return -1, 0 or 1 depending on their ordering. Comparisons are semantically correct so that

    my $v1 = Perl::Version->new( '1.002001' );
    my $v2 = Perl::Version->new( '1.1.3' );
    print ($v1->vcmp( $v2 ) > 0 ? 'yes' : 'no'), "\n";

prints

yes

Overloaded Operators

"<=>" and "cmp"

The "<=>" and "cmp" operators are overloaded (by the vcmp method) so that comparisons between versions work as expected. This means that the other numeric and string comparison operators also work as expected.

    my $v1 = Perl::Version->new( '1.002001' );
    my $v2 = Perl::Version->new( '1.1.3' );
    print "OK!\n" if $v1 > $v2;

prints

OK!

"" (stringification)

Perl::Version objects are converted to strings by calling the stringify method. This usually results in formatting close to that of the original version string.

Constants

"REGEX"

An unanchored regular expression that matches any of the version formats supported by Perl::Version. Three captures get the prefix part, the main body of the version and any alpha suffix respectively.

    my $version = 'v1.2.3.4_5';
    my ($prefix, $main, $suffix) = ($version =~ Perl::Version::REGEX);
    print "$prefix\n$main\n$suffix\n";

prints

    v
    1.2.3.4
    _5

"MATCH"

An anchored regular expression that matches a correctly formatted version string. Five captures get any leading whitespace, the prefix part, the main body of the version, any alpha suffix and any trailing spaces respectively.

    my $version = '  v1.2.3.4_5  ';
    my ($before, $prefix, $main, $suffix, $after) 
                 = ($version =~ Perl::Version::MATCH);
    print "|$before|$prefix|$main|$suffix|$after|\n";

prints

    | |v|1.2.3.4|_5| |

DIAGNOSTICS

Error messages

"Illegal version string: %s"

The version string supplied to "new" can't be parsed as a valid version. Valid versions match this regex:

    qr/ ( (?i: Revision: \s+ ) | v | )
          ( \d+ (?: [.] \d+)* )
          ( (?: _ \d+ )? ) /x;

"new must be called as a class or object method"

"new" can't be called as a normal subroutine. Use

    $version_object->new( '1.2.3' );

    Perl::Version->new( '1.2.3' );

instead of

    Perl::Version::new( '1.2.3' );

"Unknown component name: %s"

You've attempted to access a component by name using a name that isn't recognised. Valid component names are 'revision', 'version', 'subversion' and 'alpha'. Case is not significant.

"Can't compare with %s"

You've tried to compare a Perl::Version with something other than a version string, a number or another Perl::Version.

"Can't set the number of components to 0"

Versions must have at least one component.

"You must specify a component number"

You've called component or increment without specifying the number (or name) of the component to access.

"Component %s is out of range 0..%s"

You've attempted to increment a component of a version but you've specified a component that doesn't exist within the version:

    # Fails
    my $version = Perl::Version->new( '1.4' );
    $version->increment( 2 );

Slightly confusingly you'll see this message even if you specified the component number implicitly by using one of the named convenience accessors.

CONFIGURATION AND ENVIRONMENT

Perl::Version requires no configuration files or environment variables.

DEPENDENCIES

No non-core modules.

INCOMPATIBILITIES

None reported.

BUGS AND LIMITATIONS

No bugs have been reported.

Please report any bugs or feature requests to "[email protected]", or through the web interface at <http://rt.cpan.org>.

AUTHOR

Andy Armstrong "<[email protected]>"

Hans Dieter Pearcey "<[email protected]>"

LICENCE AND COPYRIGHT

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.

DISCLAIMER OF WARRANTY

BECAUSE THIS SOFTWARE IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE SOFTWARE, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE SOFTWARE ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE IS WITH YOU. SHOULD THE SOFTWARE PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR, OR CORRECTION.

IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE SOFTWARE AS PERMITTED BY THE ABOVE LICENCE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE SOFTWARE (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE SOFTWARE TO OPERATE WITH ANY OTHER SOFTWARE), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

VERSION

SYNOPSIS

DESCRIPTION

Version Formats

Component Naming

Comparison with version.pm

INTERFACE

Accessors

Incrementing

Formatting

Comparison

Overloaded Operators

Constants

DIAGNOSTICS

Error messages

CONFIGURATION AND ENVIRONMENT

DEPENDENCIES

INCOMPATIBILITIES

BUGS AND LIMITATIONS

AUTHOR

LICENCE AND COPYRIGHT

DISCLAIMER OF WARRANTY

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