use version;
$version = version->new("12.2.1"); # must be quoted for Perl < 5.8.1
- print $version; # 12.2.1
+ print $version; # v12.2.1
print $version->numify; # 12.002001
- if ( $version gt "12.2" ) # true
+ if ( $version gt "12.2" ) # true
$alphaver = version->new("1.02_03"); # must be quoted!
- print $alphaver; # 1.02_030
+ print $alphaver; # 1.02_0300
print $alphaver->is_alpha(); # true
- $ver = qv(1.2); # 1.2.0
- $ver = qv("1.2"); # 1.2.0
+ $ver = qv("1.2.0"); # v1.2.0
$perlver = version->new(5.005_03); # must not be quoted!
print $perlver; # 5.005030
=head1 DESCRIPTION
-Overloaded version objects for all versions of Perl. This module
+Overloaded version objects for all modern versions of Perl. This module
implements all of the features of version objects which will be part
-of Perl 5.10.0 except automatic version object creation.
+of Perl 5.10.0.
-=head2 What IS a version
-
-For the purposes of this module, a version "number" is a sequence of
-positive integral values separated by decimal points and optionally a
-single underscore. This corresponds to what Perl itself uses for a
-version, as well as extending the "version as number" that is discussed
-in the various editions of the Camel book.
-
-There are actually two distinct ways to initialize versions:
-
-=over 4
-
-=item * Numeric Versions
-
-Any initial parameter which "looks like a number", see L<Numeric
-Versions>. This also covers versions with a single decimal place and
-a single embedded underscore, see L<Numeric Alpha Versions>, even though
-these must be quoted to preserve the underscore formatting.
-
-=item * Quoted Versions
-
-Any initial parameter which contains more than one decimal point
-and an optional embedded underscore, see L<Quoted Versions>.
-
-=back
-
-Both of these methods will produce similar version objects, in that
-the default stringification will yield the version L<Normal Form> only
-if required:
-
- $v = version->new(1.002); # 1.002, but compares like 1.2.0
- $v = version->new(1.002003); # 1.002003
- $v2 = version->new( "1.2.3"); # v1.2.3
- $v3 = version->new( 1.2.3); # v1.2.3 for Perl >= 5.8.1
-
-In specific, version numbers initialized as L<Numeric Versions> will
-stringify in Numeric form. Version numbers initialized as L<Quoted Versions>
-will be stringified as L<Normal Form>.
-
-Please see L<Quoting> for more details on how Perl will parse various
-input values.
-
-Any value passed to the new() operator will be parsed only so far as it
-contains a numeric, decimal, or underscore character. So, for example:
-
- $v1 = version->new("99 and 94/100 percent pure"); # $v1 == 99.0
- $v2 = version->new("something"); # $v2 == "" and $v2->numify == 0
-
-However, see L<New Operator> for one case where non-numeric text is
-acceptable when initializing version objects.
-
-=head2 What about v-strings?
-
-Beginning with Perl 5.6.0, an alternate method to code arbitrary strings
-of bytes was introduced, called v-strings. They were intended to be an
-easy way to enter, for example, Unicode strings (which contain two bytes
-per character). Some programs have used them to encode printer control
-characters (e.g. CRLF). They were also intended to be used for $VERSION.
-Their use has been problematic from the start and they will be phased out
-beginning in Perl 5.10.0.
-
-There are two ways to enter v-strings: a bare number with two or more
-decimal places, or a bare number with one or more decimal places and a
-leading 'v' character (also bare). For example:
-
- $vs1 = 1.2.3; # encoded as \1\2\3
- $vs2 = v1.2; # encoded as \1\2
-
-The first of those two syntaxes is destined to be the default way to create
-a version object in 5.10.0, whereas the second will issue a mandatory
-deprecation warning beginning at the same time. In both cases, a v-string
-encoded version will always be stringified in the version L<Normal Form>.
-
-Consequently, the use of v-strings to initialize version objects with
-this module is only possible with Perl 5.8.1 or better (which contain special
-code to enable it). Their use is B<strongly> discouraged in all
-circumstances (especially the leading 'v' style), since the meaning will
-change depending on which Perl you are running. It is better to use
-L<"Quoted Versions"> to ensure the proper interpretation.
-
-=head2 Numeric Versions
-
-These correspond to historical versions of Perl itself prior to 5.6.0,
-as well as all other modules which follow the Camel rules for the
-$VERSION scalar. A numeric version is initialized with what looks like
-a floating point number. Leading zeros B<are> significant and trailing
-zeros are implied so that a minimum of three places is maintained
-between subversions. What this means is that any subversion (digits
-to the right of the decimal place) that contains less than three digits
-will have trailing zeros added to make up the difference, but only for
-purposes of comparison with other version objects. For example:
-
- $v = version->new( 1.2); # prints 1.2, compares as 1.200.0
- $v = version->new( 1.02); # prints 1.02, compares as 1.20.0
- $v = version->new( 1.002); # prints 1.002, compares as 1.2.0
- $v = version->new( 1.0023); # 1.2.300
- $v = version->new( 1.00203); # 1.2.30
- $v = version->new( 1.002_03); # 1.2.30 See "Quoting"
- $v = version->new( 1.002003); # 1.2.3
-
-All of the preceding examples except the second to last are true
-whether or not the input value is quoted. The important feature is that
-the input value contains only a single decimal.
-
-IMPORTANT NOTE: If your numeric version contains more than 3 significant
-digits after the decimal place, it will be split on each multiple of 3, so
-1.0003 becomes 1.0.300, due to the need to remain compatible with Perl's
-own 5.005_03 == 5.5.30 interpretation.
-
-=head2 Quoted Versions
-
-These are the newest form of versions, and correspond to Perl's own
-version style beginning with 5.6.0. Starting with Perl 5.10.0,
-and most likely Perl 6, this is likely to be the preferred form. This
-method requires that the input parameter be quoted, although Perl's after
-5.9.0 can use bare numbers with multiple decimal places as a special form
-of quoting.
-
-Unlike L<Numeric Versions>, Quoted Versions may have more than
-a single decimal point, e.g. "5.6.1" (for all versions of Perl). If a
-Quoted Version has only one decimal place (and no embedded underscore),
-it is interpreted exactly like a L<Numeric Version>.
-
-So, for example:
-
- $v = version->new( "1.002"); # 1.2
- $v = version->new( "1.2.3"); # 1.2.3
- $v = version->new("1.0003"); # 1.0.300
-
-In addition to conventional versions, Quoted Versions can be
-used to create L<Alpha Versions>.
-
-In general, Quoted Versions permit the greatest amount of freedom
-to specify a version, whereas Numeric Versions enforce a certain
-uniformity. See also L<New Operator> for an additional method of
-initializing version objects.
-
-=head2 Numeric Alpha Versions
-
-The one time that a numeric version must be quoted is when a alpha form is
-used with an otherwise numeric version (i.e. a single decimal place). This
-is commonly used for CPAN releases, where CPAN or CPANPLUS will ignore alpha
-versions for automatic updating purposes. Since some developers have used
-only two significant decimal places for their non-alpha releases, the
-version object will automatically take that into account if the initializer
-is quoted. For example Module::Example was released to CPAN with the
-following sequence of $VERSION's:
-
- # $VERSION Stringified
- 0.01 0.010
- 0.02 0.020
- 0.02_01 0.02_0100
- 0.02_02 0.02_0200
- 0.03 0.030
- etc.
-
-As you can see, the version object created from the values in the first
-column may contain a trailing 0, but will otherwise be both mathematically
-equivalent and sorts alpha-numerically as would be expected.
-
-=head2 Object Methods
-
-Overloading has been used with version objects to provide a natural
-interface for their use. All mathematical operations are forbidden,
-since they don't make any sense for base version objects.
-
-=over 4
-
-=item * New Operator
-
-Like all OO interfaces, the new() operator is used to initialize
-version objects. One way to increment versions when programming is to
-use the CVS variable $Revision, which is automatically incremented by
-CVS every time the file is committed to the repository.
-
-In order to facilitate this feature, the following
-code can be employed:
-
- $VERSION = version->new(qw$Revision: 2.7 $);
+=head2 BEST PRACTICES
-and the version object will be created as if the following code
-were used:
-
- $VERSION = version->new("v2.7");
-
-In other words, the version will be automatically parsed out of the
-string, and it will be quoted to preserve the meaning CVS normally
-carries for versions. The CVS $Revision$ increments differently from
-numeric versions (i.e. 1.10 follows 1.9), so it must be handled as if
-it were a L<Quoted Version>.
-
-A new version object can be created as a copy of an existing version
-object, either as a class method:
-
- $v1 = version->new(12.3);
- $v2 = version->new($v1);
-
-or as an object method:
-
- $v1 = version->new(12.3);
- $v2 = $v1->new();
-
-and in each case, $v1 and $v2 will be identical.
-
-=back
+If you intend for your module to be used by different releases of Perl,
+and/or for your $VERSION scalar to mean what you think it means, there
+are a few simple rules to follow:
=over 4
-=item * qv()
-
-An alternate way to create a new version object is through the exported
-qv() sub. This is not strictly like other q? operators (like qq, qw),
-in that the only delimiters supported are parentheses (or spaces). It is
-the best way to initialize a short version without triggering the floating
-point interpretation. For example:
-
- $v1 = qv(1.2); # 1.2.0
- $v2 = qv("1.2"); # also 1.2.0
+=item * Be consistent
-As you can see, either a bare number or a quoted string can be used, and
-either will yield the same version number.
+Whichever of the two types of version objects that you choose to employ,
+you should stick to either L<Numeric Versions> or L<Extended Versions>
+and not mix them together. While this is I<possible>, it is very
+confusing to the average user.
-=back
+If you intend to use L<Extended Versions>, you are strongly encouraged
+to use the L<qv()> operator with a quoted term, e.g.:
-For the subsequent examples, the following three objects will be used:
+ use version; our $VERSION = qv("1.2.3");
- $ver = version->new("1.2.3.4"); # see "Quoting" below
- $alpha = version->new("1.2.3_4"); # see "Alpha versions" below
- $nver = version->new(1.002); # see "Numeric Versions" above
+on a single line as above.
-=over 4
+At the very least, decide on which of the several ways to initialize
+your version objects you prefer and stick with it. It is also best to
+be explicit about what value you intend to assign your version object
+and to not rely on hidden behavior of the parser.
-=item * Normal Form
+=item * Be careful
-For any version object which is initialized with multiple decimal
-places (either quoted or if possible v-string), or initialized using
-the L<qv()> operator, the stringified representation is returned in
-a normalized or reduced form (no extraneous zeros), and with a leading 'v':
+If you are using Module::Build or ExtUtils::MakeMaker, so that you can
+release your module to CPAN, you have to recognize that neither of those
+programs completely handles version objects natively (yet). If you use
+version objects with Module::Build, you should add an explicit dependency
+to the release of version.pm in your Build.PL:
- print $ver->normal; # prints as v1.2.3
- print $ver->stringify; # ditto
- print $ver; # ditto
- print $nver->normal; # prints as v1.2.0
- print $nver->stringify; # prints as 1.002, see "Stringification"
+ my $builder = Module::Build->new(
+ ...
+ requires => {
+ ... ,
+ 'version' => 0.50,
+ ...,
+ },
+ ...
+ );
-In order to preserve the meaning of the processed version, the
-normalized representation will always contain at least three sub terms.
-In other words, the following is guaranteed to always be true:
-
- my $newver = version->new($ver->stringify);
- if ($newver eq $ver ) # always true
- {...}
+and it should Just Work(TM). Module::Build will [hopefully soon]
+include full support for version objects; there are no current plans
+to patch ExtUtils::MakeMaker to support version objects.
=back
-=over 4
-
-=item * Numification
-
-Although all mathematical operations on version objects are forbidden
-by default, it is possible to retrieve a number which roughly
-corresponds to the version object through the use of the $obj->numify
-method. For formatting purposes, when displaying a number which
-corresponds a version object, all sub versions are assumed to have
-three decimal places. So for example:
+=head2 Using modules that use version.pm
- print $ver->numify; # prints 1.002003
- print $nver->numify; # prints 1.002
+As much as possible, the version.pm module remains compatible with all
+current code. However, if your module is using a module that has defined
+C<$VERSION> using the version class, there are a couple of things to be
+aware of. For purposes of discussion, we will assume that we have the
+following module installed:
-Unlike the stringification operator, there is never any need to append
-trailing zeros to preserve the correct version value.
-
-=back
+ package Example;
+ use version; $VERSION = qv('1.2.2');
+ ...module code here...
+ 1;
=over 4
-=item * Stringification
+=item Numeric versions always work
-In order to mirror as much as possible the existing behavior of ordinary
-$VERSION scalars, the stringification operation will display differently,
-depending on whether the version was initialized as a L<Numeric Version>
-or L<Quoted Version>.
+Code of the form:
-What this means in practice is that if the normal CPAN and Camel rules are
-followed ($VERSION is a floating point number with no more than 3 decimal
-places), the stringified output will be exactly the same as the numified
-output. There will be no visible difference, although the internal
-representation will be different, and the L<Comparison operators> will
-function using the internal coding.
+ use Example 1.002003;
-If a version object is initialized using a L<Quoted Version> form, or if
-the number of significant decimal places exceed three, then the stringified
-form will be the L<Normal Form>. The $obj->normal operation can always be
-used to produce the L<Normal Form>, even if the version was originally a
-L<Numeric Version>.
+will always work correctly. The C<use> will perform an automatic
+C<$VERSION> comparison using the floating point number given as the first
+term after the module name (e.g. above 1.002.003). In this case, the
+installed module is too old for the requested line, so you would see an
+error like:
- print $ver->stringify; # prints v1.2.3
- print $nver->stringify; # prints 1.002
+ Example version 1.002003 (v1.2.3) required--this is only version 1.002002 (v1.2.2)...
-=back
+=item Extended version work sometimes
-=over 4
+With Perl >= 5.6.2, you can also use a line like this:
-=item * Comparison operators
+ use Example 1.2.3;
-Both cmp and <=> operators perform the same comparison between terms
-(upgrading to a version object automatically). Perl automatically
-generates all of the other comparison operators based on those two.
-In addition to the obvious equalities listed below, appending a single
-trailing 0 term does not change the value of a version for comparison
-purposes. In other words "v1.2" and "1.2.0" will compare as identical.
-
-For example, the following relations hold:
-
- As Number As String Truth Value
- --------- ------------ -----------
- $ver > 1.0 $ver gt "1.0" true
- $ver < 2.5 $ver lt true
- $ver != 1.3 $ver ne "1.3" true
- $ver == 1.2 $ver eq "1.2" false
- $ver == 1.2.3 $ver eq "1.2.3" see discussion below
-
-It is probably best to chose either the numeric notation or the string
-notation and stick with it, to reduce confusion. Perl6 version objects
-B<may> only support numeric comparisons. See also L<"Quoting">.
-
-WARNING: Comparing version with unequal numbers of decimal places (whether
-explicitly or implicitly initialized), may yield unexpected results at
-first glance. For example, the following inequalities hold:
-
- version->new(0.96) > version->new(0.95); # 0.960.0 > 0.950.0
- version->new("0.96.1") < version->new(0.95); # 0.096.1 < 0.950.0
-
-For this reason, it is best to use either exclusively L<Numeric Versions> or
-L<Quoted Versions> with multiple decimal places.
+and it will again work (i.e. give the error message as above), even with
+releases of Perl which do not normally support v-strings (see L<What about
+v-strings> below). This has to do with that fact that C<use> only checks
+to see if the second term I<looks like a number> and passes that to the
+replacement L<UNIVERSAL::VERSION>. This is not true in Perl 5.005_04,
+however, so you are B<strongly encouraged> to always use a numeric version
+in your code, even for those versions of Perl which support the extended
+version.
=back
-=over 4
-
-=item * Logical Operators
-
-If you need to test whether a version object
-has been initialized, you can simply test it directly:
-
- $vobj = version->new($something);
- if ( $vobj ) # true only if $something was non-blank
-
-You can also test whether a version object is an L<Alpha version>, for
-example to prevent the use of some feature not present in the main
-release:
-
- $vobj = version->new("1.2_3"); # MUST QUOTE
- ...later...
- if ( $vobj->is_alpha ) # True
-
-=back
-
-=head2 Quoting
-
-Because of the nature of the Perl parsing and tokenizing routines,
-certain initialization values B<must> be quoted in order to correctly
-parse as the intended version, and additionally, some initial values
-B<must not> be quoted to obtain the intended version.
-
-Except for L<Alpha versions>, any version initialized with something
-that looks like a number (a single decimal place) will be parsed in
-the same way whether or not the term is quoted. In order to be
-compatible with earlier Perl version styles, any use of versions of
-the form 5.006001 will be translated as 5.6.1. In other words, a
-version with a single decimal place will be parsed as implicitly
-having three places between subversions.
-
-The complicating factor is that in bare numbers (i.e. unquoted), the
-underscore is a legal numeric character and is automatically stripped
-by the Perl tokenizer before the version code is called. However, if
-a number containing one or more decimals and an underscore is quoted, i.e.
-not bare, that is considered a L<Alpha Version> and the underscore is
-significant.
-
-If you use a mathematic formula that resolves to a floating point number,
-you are dependent on Perl's conversion routines to yield the version you
-expect. You are pretty safe by dividing by a power of 10, for example,
-but other operations are not likely to be what you intend. For example:
-
- $VERSION = version->new((qw$Revision: 1.4)[1]/10);
- print $VERSION; # yields 0.14
- $V2 = version->new(100/9); # Integer overflow in decimal number
- print $V2; # yields something like 11.111.111.100
-
-Perl 5.8.1 and beyond will be able to automatically quote v-strings but
-that is not possible in earlier versions of Perl. In other words:
-
- $version = version->new("v2.5.4"); # legal in all versions of Perl
- $newvers = version->new(v2.5.4); # legal only in Perl >= 5.8.1
-
-
-=head2 Types of Versions Objects
-
-There are two types of Version Objects:
-
-=over 4
-
-=item * Ordinary versions
-
-These are the versions that normal modules will use. Can contain as
-many subversions as required. In particular, those using RCS/CVS can
-use the following:
-
- $VERSION = version->new(qw$Revision: 2.7 $);
-
-and the current RCS Revision for that file will be inserted
-automatically. If the file has been moved to a branch, the Revision
-will have three or more elements; otherwise, it will have only two.
-This allows you to automatically increment your module version by
-using the Revision number from the primary file in a distribution, see
-L<ExtUtils::MakeMaker/"VERSION_FROM">.
-
-=item * Alpha Versions
-
-For module authors using CPAN, the convention has been to note
-unstable releases with an underscore in the version string, see
-L<CPAN>. Alpha releases will test as being newer than the more recent
-stable release, and less than the next stable release. For example:
-
- $alphaver = version->new("12.03_01"); # must be quoted
-
-obeys the relationship
-
- 12.03 < $alphaver < 12.04
-
-Alpha versions with a single decimal place will be treated exactly as if
-they were L<Numeric Versions>, for parsing purposes. The stringification for
-alpha versions with a single decimal place may seem surprising, since any
-trailing zeros will visible. For example, the above $alphaver will print as
-
- 12.03_0100
-
-which is mathematically equivalent and ASCII sorts exactly the same as
-without the trailing zeros.
-
-Alpha versions with more than a single decimal place will be treated
-exactly as if they were L<Quoted Versions>, and will display without any
-trailing (or leading) zeros, in the L<Version Normal> form. For example,
-
- $newver = version->new("12.3.1_1");
- print $newver; # v12.3.1_1
-
-=head2 Replacement UNIVERSAL::VERSION
-
-In addition to the version objects, this modules also replaces the core
-UNIVERSAL::VERSION function with one that uses version objects for its
-comparisons. The return from this operator is always the numified form,
-and the warning message generated includes both the numified and normal
-forms (for clarity).
-
-For example:
-
- package Foo;
- $VERSION = 1.2;
-
- package Bar;
- $VERSION = "1.3.5"; # works with all Perl's (since it is quoted)
-
- package main;
- use version;
-
- print $Foo::VERSION; # prints 1.2
-
- print $Bar::VERSION; # prints 1.003005
-
- eval "use CGI 10"; # some far future release
- print $@; # prints "CGI version 10 (10.0.0) required..."
-
-IMPORTANT NOTE: This may mean that code which searches for a specific
-string (to determine whether a given module is available) may need to be
-changed.
-
-The replacement UNIVERSAL::VERSION, when used as a function, like this:
-
- print $module->VERSION;
-
-will also exclusively return the numified form. Technically, the
-$module->VERSION function returns a string (PV) that can be converted to a
-number following the normal Perl rules, when used in a numeric context.
-
-=head1 SUBCLASSING
-
-This module is specifically designed and tested to be easily subclassed.
-In practice, you only need to override the methods you want to change, but
-you have to take some care when overriding new() (since that is where all
-of the parsing takes place). For example, this is a perfect acceptable
-derived class:
-
- package myversion;
- use base version;
- sub new {
- my($self,$n)=@_;
- my $obj;
- # perform any special input handling here
- $obj = $self->SUPER::new($n);
- # and/or add additional hash elements here
- return $obj;
- }
-
-See also L<version::AlphaBeta> on CPAN for an alternate representation of
-version strings.
-
-=head1 EXPORT
-
-qv - quoted version initialization operator
-
-=head1 AUTHOR
-
-John Peacock E<lt>jpeacock@cpan.orgE<gt>
-
-=head1 SEE ALSO
-
-L<perl>.
-
-=cut
-=head1 NAME
-
-version - Perl extension for Version Objects
-
-=head1 SYNOPSIS
-
- use version;
- $version = version->new("12.2.1"); # must be quoted for Perl < 5.8.1
- print $version; # 12.2.1
- print $version->numify; # 12.002001
- if ( $version gt "12.2" ) # true
-
- $alphaver = version->new("1.02_03"); # must be quoted!
- print $alphaver; # 1.02_030
- print $alphaver->is_alpha(); # true
-
- $ver = qv(1.2); # 1.2.0
- $ver = qv("1.2"); # 1.2.0
-
- $perlver = version->new(5.005_03); # must not be quoted!
- print $perlver; # 5.005030
-
-=head1 DESCRIPTION
-
-Overloaded version objects for all versions of Perl. This module
-implements all of the features of version objects which will be part
-of Perl 5.10.0 except automatic version object creation.
-
=head2 What IS a version
For the purposes of this module, a version "number" is a sequence of
-positive integral values separated by decimal points and optionally a
-single underscore. This corresponds to what Perl itself uses for a
-version, as well as extending the "version as number" that is discussed
-in the various editions of the Camel book.
+positive integer values separated by one or more decimal points and
+optionally a single underscore. This corresponds to what Perl itself
+uses for a version, as well as extending the "version as number" that
+is discussed in the various editions of the Camel book.
-There are actually two distinct ways to initialize versions:
+There are actually two distinct kinds of version objects:
=over 4
=item * Numeric Versions
Any initial parameter which "looks like a number", see L<Numeric
-Versions>. This also covers versions with a single decimal place and
+Versions>. This also covers versions with a single decimal point and
a single embedded underscore, see L<Numeric Alpha Versions>, even though
these must be quoted to preserve the underscore formatting.
-=item * Quoted Versions
+=item * Extended Versions
Any initial parameter which contains more than one decimal point
-and an optional embedded underscore, see L<Quoted Versions>.
+and an optional embedded underscore, see L<Extended Versions>. This
+is what is commonly used in most open source software as the "external"
+version (the one used as part of the tag or tarfile name). The use
+of the exported L<qv()> function also produces this kind of version
+object.
=back
$v = version->new(1.002); # 1.002, but compares like 1.2.0
$v = version->new(1.002003); # 1.002003
- $v2 = version->new( "1.2.3"); # v1.2.3
- $v3 = version->new( 1.2.3); # v1.2.3 for Perl >= 5.8.1
+ $v2 = version->new("1.2.3"); # v1.2.3
In specific, version numbers initialized as L<Numeric Versions> will
-stringify in Numeric form. Version numbers initialized as L<Quoted Versions>
+stringify as they were originally created (i.e. the same string that was
+passed to C<new()>. Version numbers initialized as L<Extended Versions>
will be stringified as L<Normal Form>.
-Please see L<Quoting> for more details on how Perl will parse various
-input values.
-
-Any value passed to the new() operator will be parsed only so far as it
-contains a numeric, decimal, or underscore character. So, for example:
-
- $v1 = version->new("99 and 94/100 percent pure"); # $v1 == 99.0
- $v2 = version->new("something"); # $v2 == "" and $v2->numify == 0
-
-However, see L<New Operator> for one case where non-numeric text is
-acceptable when initializing version objects.
-
-=head2 What about v-strings?
-
-Beginning with Perl 5.6.0, an alternate method to code arbitrary strings
-of bytes was introduced, called v-strings. They were intended to be an
-easy way to enter, for example, Unicode strings (which contain two bytes
-per character). Some programs have used them to encode printer control
-characters (e.g. CRLF). They were also intended to be used for $VERSION.
-Their use has been problematic from the start and they will be phased out
-beginning in Perl 5.10.0.
-
-There are two ways to enter v-strings: a bare number with two or more
-decimal places, or a bare number with one or more decimal places and a
-leading 'v' character (also bare). For example:
-
- $vs1 = 1.2.3; # encoded as \1\2\3
- $vs2 = v1.2; # encoded as \1\2
-
-The first of those two syntaxes is destined to be the default way to create
-a version object in 5.10.0, whereas the second will issue a mandatory
-deprecation warning beginning at the same time. In both cases, a v-string
-encoded version will always be stringified in the version L<Normal Form>.
-
-Consequently, the use of v-strings to initialize version objects with
-this module is only possible with Perl 5.8.1 or better (which contain special
-code to enable it). Their use is B<strongly> discouraged in all
-circumstances (especially the leading 'v' style), since the meaning will
-change depending on which Perl you are running. It is better to use
-L<"Quoted Versions"> to ensure the proper interpretation.
-
=head2 Numeric Versions
These correspond to historical versions of Perl itself prior to 5.6.0,
will have trailing zeros added to make up the difference, but only for
purposes of comparison with other version objects. For example:
- $v = version->new( 1.2); # prints 1.2, compares as 1.200.0
- $v = version->new( 1.02); # prints 1.02, compares as 1.20.0
- $v = version->new( 1.002); # prints 1.002, compares as 1.2.0
- $v = version->new( 1.0023); # 1.2.300
- $v = version->new( 1.00203); # 1.2.30
- $v = version->new( 1.002_03); # 1.2.30 See "Quoting"
- $v = version->new( 1.002003); # 1.2.3
+ # Prints Equivalent to
+ $v = version->new( 1.2); # 1.2 v1.200.0
+ $v = version->new( 1.02); # 1.02 v1.20.0
+ $v = version->new( 1.002); # 1.002 v1.2.0
+ $v = version->new( 1.0023); # 1.0023 v1.2.300
+ $v = version->new( 1.00203); # 1.00203 v1.2.30
+ $v = version->new( 1.002003); # 1.002003 v1.2.3
-All of the preceding examples except the second to last are true
-whether or not the input value is quoted. The important feature is that
-the input value contains only a single decimal.
+All of the preceding examples are true whether or not the input value is
+quoted. The important feature is that the input value contains only a
+single decimal. See also L<Alpha Versions> for how to handle
-IMPORTANT NOTE: If your numeric version contains more than 3 significant
-digits after the decimal place, it will be split on each multiple of 3, so
-1.0003 becomes 1.0.300, due to the need to remain compatible with Perl's
-own 5.005_03 == 5.5.30 interpretation.
+IMPORTANT NOTE: As shown above, if your numeric version contains more
+than 3 significant digits after the decimal place, it will be split on
+each multiple of 3, so 1.0003 is equivalent to v1.0.300, due to the need
+to remain compatible with Perl's own 5.005_03 == 5.5.30 interpretation.
+Any trailing zeros are ignored for mathematical comparison purposes.
-=head2 Quoted Versions
+=head2 Extended Versions
These are the newest form of versions, and correspond to Perl's own
version style beginning with 5.6.0. Starting with Perl 5.10.0,
and most likely Perl 6, this is likely to be the preferred form. This
-method requires that the input parameter be quoted, although Perl's after
-5.9.0 can use bare numbers with multiple decimal places as a special form
-of quoting.
-
-Unlike L<Numeric Versions>, Quoted Versions may have more than
-a single decimal point, e.g. "5.6.1" (for all versions of Perl). If a
-Quoted Version has only one decimal place (and no embedded underscore),
-it is interpreted exactly like a L<Numeric Version>.
+method normally requires that the input parameter be quoted, although
+Perl's after 5.8.1 can use v-strings as a special form of quoting, but
+this is highly discouraged.
-So, for example:
+Unlike L<Numeric Versions>, Extended Versions have more than
+a single decimal point, e.g.:
- $v = version->new( "1.002"); # 1.2
- $v = version->new( "1.2.3"); # 1.2.3
- $v = version->new("1.0003"); # 1.0.300
+ # Prints
+ $v = version->new( "v1.200"); # v1.200.0
+ $v = version->new("v1.20.0"); # v1.20.0
+ $v = qv("v1.2.3"); # v1.2.3
+ $v = qv("1.2.3"); # v1.2.3
+ $v = qv("1.20"); # v1.20.0
-In addition to conventional versions, Quoted Versions can be
-used to create L<Alpha Versions>.
-
-In general, Quoted Versions permit the greatest amount of freedom
+In general, Extended Versions permit the greatest amount of freedom
to specify a version, whereas Numeric Versions enforce a certain
uniformity. See also L<New Operator> for an additional method of
initializing version objects.
+Just like L<Numeric Versions>, Extended Versions can be used as
+L<Alpha Versions>.
+
=head2 Numeric Alpha Versions
The one time that a numeric version must be quoted is when a alpha form is
-used with an otherwise numeric version (i.e. a single decimal place). This
+used with an otherwise numeric version (i.e. a single decimal point). This
is commonly used for CPAN releases, where CPAN or CPANPLUS will ignore alpha
versions for automatic updating purposes. Since some developers have used
only two significant decimal places for their non-alpha releases, the
following sequence of $VERSION's:
# $VERSION Stringified
- 0.01 0.010
- 0.02 0.020
- 0.02_01 0.02_0100
- 0.02_02 0.02_0200
- 0.03 0.030
+ 0.01 0.01
+ 0.02 0.02
+ 0.02_01 0.02_01
+ 0.02_02 0.02_02
+ 0.03 0.03
etc.
-As you can see, the version object created from the values in the first
-column may contain a trailing 0, but will otherwise be both mathematically
-equivalent and sorts alpha-numerically as would be expected.
+The stringified form of numeric versions will always be the same string
+that was used to initialize the version object.
=head2 Object Methods
Overloading has been used with version objects to provide a natural
interface for their use. All mathematical operations are forbidden,
-since they don't make any sense for base version objects.
+since they don't make any sense for base version objects. Consequently,
+there is no overloaded numification available. If you want to use a
+version object in a numeric context for some reason, see the L<numify>
+object method.
=over 4
string, and it will be quoted to preserve the meaning CVS normally
carries for versions. The CVS $Revision$ increments differently from
numeric versions (i.e. 1.10 follows 1.9), so it must be handled as if
-it were a L<Quoted Version>.
+it were a L<Extended Version>.
A new version object can be created as a copy of an existing version
object, either as a class method:
or as an object method:
$v1 = version->new(12.3);
+ $v2 = $v1->new(12.3);
+
+and in each case, $v1 and $v2 will be identical. NOTE: if you create
+a new object using an existing object like this:
+
$v2 = $v1->new();
-and in each case, $v1 and $v2 will be identical.
+the new object B<will not> be a clone of the existing object. In the
+example case, $v2 will be an empty object of the same type as $v1.
=back
$v1 = qv(1.2); # 1.2.0
$v2 = qv("1.2"); # also 1.2.0
-As you can see, either a bare number or a quoted string can be used, and
-either will yield the same version number.
+As you can see, either a bare number or a quoted string can usually
+be used interchangably, except in the case of a trailing zero, which
+must be quoted to be converted properly. For this reason, it is strongly
+recommended that all initializers to qv() be quoted strings instead of
+bare numbers.
+
+To prevent the C<qv()> function from being exported to the caller's namespace,
+either use version with a null parameter:
+
+ use version ();
+
+or just require version, like this:
+
+ require version;
+
+Both methods will prevent the import() method from firing and exporting the
+C<qv()> sub. This is true of subclasses of version as well, see
+L<SUBCLASSING> for details.
=back
$ver = version->new("1.2.3.4"); # see "Quoting" below
$alpha = version->new("1.2.3_4"); # see "Alpha versions" below
- $nver = version->new(1.002); # see "Numeric Versions" above
+ $nver = version->new(1.002); # see "Numeric Versions" above
=over 4
the L<qv()> operator, the stringified representation is returned in
a normalized or reduced form (no extraneous zeros), and with a leading 'v':
- print $ver->normal; # prints as v1.2.3
+ print $ver->normal; # prints as v1.2.3.4
print $ver->stringify; # ditto
print $ver; # ditto
print $nver->normal; # prints as v1.2.0
=item * Numification
Although all mathematical operations on version objects are forbidden
-by default, it is possible to retrieve a number which roughly
-corresponds to the version object through the use of the $obj->numify
+by default, it is possible to retrieve a number which corresponds
+to the version object through the use of the $obj->numify
method. For formatting purposes, when displaying a number which
corresponds a version object, all sub versions are assumed to have
three decimal places. So for example:
- print $ver->numify; # prints 1.002003
+ print $ver->numify; # prints 1.002003004
print $nver->numify; # prints 1.002
Unlike the stringification operator, there is never any need to append
=item * Stringification
-In order to mirror as much as possible the existing behavior of ordinary
-$VERSION scalars, the stringification operation will display differently,
-depending on whether the version was initialized as a L<Numeric Version>
-or L<Quoted Version>.
+The default stringification for version objects returns exactly the same
+string as was used to create it, whether you used C<new()> or C<qv()>,
+with one exception. The sole exception is if the object was created using
+C<qv()> and the initializer did not have two decimal places or a leading
+'v' (both optional), then the stringified form will have a leading 'v'
+prepended, in order to support round-trip processing.
-What this means in practice is that if the normal CPAN and Camel rules are
-followed ($VERSION is a floating point number with no more than 3 decimal
-places), the stringified output will be exactly the same as the numified
-output. There will be no visible difference, although the internal
-representation will be different, and the L<Comparison operators> will
-function using the internal coding.
+For example:
-If a version object is initialized using a L<Quoted Version> form, or if
-the number of significant decimal places exceed three, then the stringified
-form will be the L<Normal Form>. The $obj->normal operation can always be
-used to produce the L<Normal Form>, even if the version was originally a
-L<Numeric Version>.
+ Initialized as Stringifies to
+ ============== ==============
+ version->new("1.2") 1.2
+ version->new("v1.2") v1.2
+ qv("1.2.3") 1.2.3
+ qv("v1.3.5") v1.3.5
+ qv("1.2") v1.2 ### exceptional case
- print $ver->stringify; # prints v1.2.3
- print $nver->stringify; # prints 1.002
+See also L<UNIVERSAL::VERSION>, as this also returns the stringified form
+when used as a class method.
=back
=item * Comparison operators
-Both cmp and <=> operators perform the same comparison between terms
-(upgrading to a version object automatically). Perl automatically
+Both C<cmp> and C<E<lt>=E<gt>> operators perform the same comparison between
+terms (upgrading to a version object automatically). Perl automatically
generates all of the other comparison operators based on those two.
In addition to the obvious equalities listed below, appending a single
trailing 0 term does not change the value of a version for comparison
For example, the following relations hold:
- As Number As String Truth Value
- --------- ------------ -----------
- $ver > 1.0 $ver gt "1.0" true
- $ver < 2.5 $ver lt true
- $ver != 1.3 $ver ne "1.3" true
- $ver == 1.2 $ver eq "1.2" false
- $ver == 1.2.3 $ver eq "1.2.3" see discussion below
+ As Number As String Truth Value
+ ------------- ---------------- -----------
+ $ver > 1.0 $ver gt "1.0" true
+ $ver < 2.5 $ver lt true
+ $ver != 1.3 $ver ne "1.3" true
+ $ver == 1.2 $ver eq "1.2" false
+ $ver == 1.2.3.4 $ver eq "1.2.3.4" see discussion below
It is probably best to chose either the numeric notation or the string
notation and stick with it, to reduce confusion. Perl6 version objects
-B<may> only support numeric comparisons. See also L<"Quoting">.
+B<may> only support numeric comparisons. See also L<Quoting>.
-WARNING: Comparing version with unequal numbers of decimal places (whether
+WARNING: Comparing version with unequal numbers of decimal points (whether
explicitly or implicitly initialized), may yield unexpected results at
first glance. For example, the following inequalities hold:
version->new("0.96.1") < version->new(0.95); # 0.096.1 < 0.950.0
For this reason, it is best to use either exclusively L<Numeric Versions> or
-L<Quoted Versions> with multiple decimal places.
+L<Extended Versions> with multiple decimal points.
=back
Because of the nature of the Perl parsing and tokenizing routines,
certain initialization values B<must> be quoted in order to correctly
-parse as the intended version, and additionally, some initial values
-B<must not> be quoted to obtain the intended version.
-
-Except for L<Alpha versions>, any version initialized with something
-that looks like a number (a single decimal place) will be parsed in
-the same way whether or not the term is quoted. In order to be
-compatible with earlier Perl version styles, any use of versions of
-the form 5.006001 will be translated as 5.6.1. In other words, a
-version with a single decimal place will be parsed as implicitly
-having three places between subversions.
+parse as the intended version, especially when using the L<qv()> operator.
+In all cases, a floating point number passed to version->new() will be
+identically converted whether or not the value itself is quoted. This is
+not true for L<qv()>, however, when trailing zeros would be stripped on
+an unquoted input, which would result in a very different version object.
+
+In addition, in order to be compatible with earlier Perl version styles,
+any use of versions of the form 5.006001 will be translated as v5.6.1.
+In other words, a version with a single decimal point will be parsed as
+implicitly having three digits between subversions, but only for internal
+comparison purposes.
The complicating factor is that in bare numbers (i.e. unquoted), the
underscore is a legal numeric character and is automatically stripped
$version = version->new("v2.5.4"); # legal in all versions of Perl
$newvers = version->new(v2.5.4); # legal only in Perl >= 5.8.1
+=head2 What about v-strings?
+
+Beginning with Perl 5.6.0, an alternate method to code arbitrary strings
+of bytes was introduced, called v-strings. They were intended to be an
+easy way to enter, for example, Unicode strings (which contain two bytes
+per character). Some programs have used them to encode printer control
+characters (e.g. CRLF). They were also intended to be used for $VERSION,
+but their use as such has been problematic from the start.
+
+There are two ways to enter v-strings: a bare number with two or more
+decimal points, or a bare number with one or more decimal points and a
+leading 'v' character (also bare). For example:
+
+ $vs1 = 1.2.3; # encoded as \1\2\3
+ $vs2 = v1.2; # encoded as \1\2
+
+However, the use of bare v-strings to initialize version objects is
+B<strongly> discouraged in all circumstances (especially the leading
+'v' style), since the meaning will change depending on which Perl you
+are running. It is better to directly use L<"Extended Versions"> to
+ensure the proper interpretation.
+
+If you insist on using bare v-strings with Perl > 5.6.0, be aware of the
+following limitations:
+
+1) For Perl releases 5.6.0 through 5.8.0, the v-string code merely guesses,
+based on some characteristics of v-strings. You B<must> use a three part
+version, e.g. 1.2.3 or v1.2.3 in order for this heuristic to be successful.
+
+2) For Perl releases 5.8.1 and later, v-strings have changed in the Perl
+core to be magical, which means that the version.pm code can automatically
+determine whether the v-string encoding was used.
+
+3) In all cases, a version created using v-strings will have a stringified
+form that has a leading 'v' character, for the simple reason that sometimes
+it is impossible to tell whether one was present initially.
=head2 Types of Versions Objects
12.03 < $alphaver < 12.04
-Alpha versions with a single decimal place will be treated exactly as if
-they were L<Numeric Versions>, for parsing purposes. The stringification for
-alpha versions with a single decimal place may seem surprising, since any
-trailing zeros will visible. For example, the above $alphaver will print as
-
- 12.03_0100
+Alpha versions with a single decimal point will be treated exactly as if
+they were L<Numeric Versions>, for parsing and output purposes. The
+underscore will be output when an alpha version is stringified, in the same
+place as it was when input.
-which is mathematically equivalent and ASCII sorts exactly the same as
-without the trailing zeros.
-
-Alpha versions with more than a single decimal place will be treated
-exactly as if they were L<Quoted Versions>, and will display without any
+Alpha versions with more than a single decimal point will be treated
+exactly as if they were L<Extended Versions>, and will display without any
trailing (or leading) zeros, in the L<Version Normal> form. For example,
$newver = version->new("12.3.1_1");
print $newver; # v12.3.1_1
+=back
+
=head2 Replacement UNIVERSAL::VERSION
In addition to the version objects, this modules also replaces the core
UNIVERSAL::VERSION function with one that uses version objects for its
-comparisons. The return from this operator is always the numified form,
-and the warning message generated includes both the numified and normal
-forms (for clarity).
+comparisons. The return from this operator is always the stringified form,
+but the warning message generated includes either the stringified form or
+the normal form, depending on how it was called.
For example:
print $Bar::VERSION; # prints 1.003005
- eval "use CGI 10"; # some far future release
- print $@; # prints "CGI version 10 (10.0.0) required..."
+ eval "use foo 10";
+ print $@; # prints "foo version 10 required..."
+ eval "use foo 1.3.5; # work in Perl 5.6.1 or better
+ print $@; # prints "foo version 1.3.5 required..."
+
+ eval "use bar 1.3.6";
+ print $@; # prints "bar version 1.3.6 required..."
+ eval "use bar 1.004"; # note numeric version
+ print $@; # prints "bar version 1.004 required..."
+
IMPORTANT NOTE: This may mean that code which searches for a specific
string (to determine whether a given module is available) may need to be
-changed.
+changed. It is always better to use the built-in comparison implicit in
+C<use> or C<require>, rather than manually poking at C<class->VERSION>
+and then doing a comparison yourself.
The replacement UNIVERSAL::VERSION, when used as a function, like this:
print $module->VERSION;
-will also exclusively return the numified form. Technically, the
-$module->VERSION function returns a string (PV) that can be converted to a
-number following the normal Perl rules, when used in a numeric context.
+will also exclusively return the stringified form. See L<Stringification>
+for more details.
=head1 SUBCLASSING
See also L<version::AlphaBeta> on CPAN for an alternate representation of
version strings.
+B<NOTE:> Although the L<qv> operator is not a true class method, but rather a
+function exported into the caller's namespace, a subclass of version will
+inherit an import() function which will perform the correct magic on behalf
+of the subclass.
+
=head1 EXPORT
-qv - quoted version initialization operator
+qv - Extended Version initialization operator
=head1 AUTHOR
projects / p5sagit/p5-mst-13.2.git / blobdiff