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 BEST PRACTICES
+
+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 * Be consistent
+
+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.
+
+If you intend to use L<Extended Versions>, you are strongly encouraged
+to use the L<qv()> operator with a quoted term, e.g.:
+
+ use version; our $VERSION = qv("1.2.3");
+
+on a single line as above.
+
+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 * Be careful
+
+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:
+
+ my $builder = Module::Build->new(
+ ...
+ requires => {
+ ... ,
+ 'version' => 0.50,
+ ...,
+ },
+ ...
+ );
+
+and it should Just Work(TM). Module::Build will [hopefully soon]
+include full support for version objects; there are no current plans
+to patch ExtUtils::MakeMaker to support version objects.
+
+=back
+
+=head2 Using modules that use version.pm
+
+As much as possible, the version.pm module remains compatible with all
+current code. However, if your module is using a module that has defined
+C<$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:
+
+ package Example;
+ use version; $VERSION = qv('1.2.2');
+ ...module code here...
+ 1;
+
+=over 4
+
+=item Numeric versions always work
+
+Code of the form:
+
+ use Example 1.002003;
+
+will always work correctly. The C<use> will perform an automatic
+C<$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:
+
+ Example version 1.002003 (v1.2.3) required--this is only version 1.002002 (v1.2.2)...
+
+=item Extended version work sometimes
+
+With Perl >= 5.6.2, you can also use a line like this:
+
+ use Example 1.2.3;
+
+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
=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 * Extended Versions
Any initial parameter which contains more than one decimal point
-and an optional embedded underscore, see L<Extended 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
In specific, version numbers initialized as L<Numeric Versions> will
stringify in Numeric form. 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<"Extended 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); # 1.200 v1.200.0
+ $v = version->new( 1.02); # 1.020 v1.20.0
+ $v = version->new( 1.002); # 1.002 v1.2.0
+ $v = version->new( 1.0023); # 1.002300 v1.2.300
+ $v = version->new( 1.00203); # 1.002030 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 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>, Extended Versions may have more than
-a single decimal point, e.g. "5.6.1" (for all versions of Perl). If a
-Extended Version has only one decimal place (and no embedded underscore),
-it is interpreted exactly like a L<Numeric Version>.
-
-So, for example:
+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.
- $v = version->new( "1.002"); # 1.2
- $v = version->new( "1.2.3"); # 1.2.3
- $v = version->new("1.0003"); # 1.0.300
+Unlike L<Numeric Versions>, Extended Versions have more than
+a single decimal point, e.g.:
-In addition to conventional versions, Extended Versions can be
-used to create L<Alpha Versions>.
+ # 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 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
$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 $nver->numify; # prints 1.002
Unlike the stringification operator, there is never any need to append
What this means in practice is that if the normal CPAN and Camel rules are
followed ($VERSION is a floating point number with no more than 3 decimal
-places), the stringified output will be exactly the same as the numified
+points), 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.
-If a version object is initialized using a L<Extended 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>.
+If a version object is initialized using a L<Extended Version> form, 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>.
- print $ver->stringify; # prints v1.2.3
+ print $ver->stringify; # prints v1.2.3.4
print $nver->stringify; # prints 1.002
=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<Extended 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 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 directly
+use L<"Extended Versions"> to ensure the proper interpretation.
+
=head2 Types of Versions Objects
12.03 < $alphaver < 12.04
-Alpha versions with a single decimal place will be treated exactly as if
+Alpha versions with a single decimal point 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
+alpha versions with a single decimal point 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
+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,
See also L<version::AlphaBeta> on CPAN for an alternate representation of
version strings.
-B<NOTE:> the L<qv> operator is not a class method and will not be inherited
-in the same way as the other methods. L<qv> will always return an object of
-type L<version> and not an object in the derived class. If you need to
-have L<qv> return an object in your derived class, add something like this:
-
- *::qv = sub { return bless version::qv(shift), __PACKAGE__ };
-
-as seen in the test file F<t/02derived.t>.
+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
projects / p5sagit/p5-mst-13.2.git / blobdiff