+++ /dev/null
-=head1 NAME
-
-version::Internals - Perl extension for Version Objects
-
-=head1 DESCRIPTION
-
-Overloaded version objects for all modern versions of Perl. This documents
-the internal data representation and underlying code for version.pm. See
-F<version.pod> for daily usage. This document is only useful for users
-interested in the gory details.
-
-=head1 WHAT IS A VERSION?
-
-For the purposes of this module, a version "number" is a sequence of
-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 kinds of version objects:
-
-=over 4
-
-=item Decimal Versions
-
-Any version which "looks like a number", see L<Decimal Versions>. This
-also includes versions with a single decimal point and a single embedded
-underscore, see L<Alpha Versions>, even though these must be quoted
-to preserve the underscore formatting.
-
-=item Dotted-Decimal Versions
-
-Also referred to as "Dotted-Integer", these contains more than one decimal
-point and may have an optional embedded underscore, see L<Dotted-Decimal
-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).
-A leading 'v' character is now required and will warn if it missing.
-
-=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
- $v2 = version->new("v1.2.3"); # v1.2.3
-
-In specific, version numbers initialized as L<Decimal Versions> will
-stringify as they were originally created (i.e. the same string that was
-passed to C<new()>. Version numbers initialized as L<Dotted-Decimal Versions>
-will be stringified as L<Normal Form>.
-
-=head2 Decimal Versions
-
-These correspond to historical versions of Perl itself prior to 5.6.0,
-as well as all other modules which follow the Camel rules for the
-$VERSION scalar. A Decimal 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:
-
- # 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 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>.
-
-IMPORTANT NOTE: As shown above, if your Decimal 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 Dotted-Decimal 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 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.
-
-Unlike L<Decimal Versions>, Dotted-Decimal Versions have more than
-a single decimal point, e.g.:
-
- # 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, Dotted-Decimal Versions permit the greatest amount of freedom
-to specify a version, whereas Decimal Versions enforce a certain
-uniformity.
-
-Just like L</Decimal Versions>, Dotted-Decimal Versions can be used as
-L</Alpha Versions>.
-
-=head2 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>.) version.pm
-follows this convention and alpha releases will test as being newer than the
-more recent stable release, and less than the next stable release. Only the
-last element may be separated by an underscore:
-
- # Declaring
- use version 0.77; our $VERSION = version->declare("v1.2_3");
-
- # Parsing
- $v1 = version->parse("v1.2_3");
- $v1 = version->parse("1.002_003");
-
-Note that you B<must> quote the version when writing an alpha Decimal version.
-The stringified form of Decimal versions will always be the same string that
-was used to initialize the version object.
-
-=head2 Regular Expressions for Version Parsing
-
-A formalized definition of the legal forms for version strings is
-included in the main F<version.pm> file. Primitives are included for
-common elements, although they are scoped to the file so they are useful
-for reference purposes only. There are two publicly accessible scalars
-that can be used in other code (not exported):
-
-=over 4
-
-=item C<$version::LAX>
-
-This regexp covers all of the legal forms allowed under the current
-version string parser. This is not to say that all of these forms
-are recommended, and some of them can only be used when quoted.
-
-For dotted decimals:
-
- v1.2
- 1.2345.6
- v1.23_4
-
-The leading 'v' is optional if two or more decimals appear. If only
-a single decimal is included, then the leading 'v' is required to
-trigger the dotted-decimal parsing. A leading zero is permitted,
-though not recommended except when quoted, because of the risk that
-Perl will treat the number as octal. A trailing underscore plus one
-or more digits denotes an alpha or development release (and must be
-quoted to be parsed properly).
-
-For decimal versions:
-
- 1
- 1.2345
- 1.2345_01
-
-an integer portion, an optional decimal point, and optionally one or
-more digits to the right of the decimal are all required. A trailing
-underscore is permitted and a leading zero is permitted. Just like
-the lax dotted-decimal version, quoting the values is required for
-alpha/development forms to be parsed correctly.
-
-=item C<$version::STRICT>
-
-This regexp covers a much more limited set of formats and constitutes
-the best practices for initializing version objects. Whether you choose
-to employ decimal or dotted-decimal for is a personal preference however.
-
-=over 4
-
-=item v1.234.5
-
-For dotted-decimal versions, a leading 'v' is required, with three or
-more sub-versions of no more than three digits. A leading 0 (zero)
-before the first sub-version (in the above example, '1') is also
-prohibited.
-
-=item 2.3456
-
-For decimal versions, an integer portion (no leading 0), a decimal point,
-and one or more digits to the right of the decimal are all required.
-
-=back
-
-=back
-
-Both of the provided scalars are already compiled as regular expressions
-and do not contain either anchors or implicit groupings, so they can be
-included in your own regular expressions freely. For example, consider
-the following code:
-
- ($pkg, $ver) =~ /
- ^[ \t]*
- use [ \t]+($PKGNAME)
- (?:[ \t]+($version::STRICT))?
- [ \t]*;
- /x;
-
-This would match a line of the form:
-
- use Foo::Bar::Baz v1.2.3; # legal only in Perl 5.8.1+
-
-where C<$PKGNAME> is another regular expression that defines the legal
-forms for package names.
-
-=head1 IMPLEMENTATION DETAILS
-
-=head2 Equivalence between Decimal and Dotted-Decimal Versions
-
-When Perl 5.6.0 was released, the decision was made to provide a
-transformation between the old-style decimal versions and new-style
-dotted-decimal versions:
-
- 5.6.0 == 5.006000
- 5.005_04 == 5.5.40
-
-The floating point number is taken and split first on the single decimal
-place, then each group of three digits to the right of the decimal makes up
-the next digit, and so on until the number of significant digits is exhausted,
-B<plus> enough trailing zeros to reach the next multiple of three.
-
-This was the method that version.pm adopted as well. Some examples may be
-helpful:
-
- equivalent
- decimal zero-padded dotted-decimal
- ------- ----------- --------------
- 1.2 1.200 v1.200.0
- 1.02 1.020 v1.20.0
- 1.002 1.002 v1.2.0
- 1.0023 1.002300 v1.2.300
- 1.00203 1.002030 v1.2.30
- 1.002003 1.002003 v1.2.3
-
-=head2 Quoting Rules
-
-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, especially when using the C<declare> or
-L</qv()> methods. While you do not have to quote decimal numbers when
-creating version objects, it is always safe to quote B<all> initial values
-when using version.pm methods, as this will ensure that what you type is
-what is used.
-
-Additionally, if you quote your initializer, then the quoted value that goes
-B<in> will be exactly what comes B<out> when your $VERSION is printed
-(stringified). If you do not quote your value, Perl's normal numeric handling
-comes into play and you may not get back what you were expecting.
-
-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 are 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 What about v-strings?
-
-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. Also, bare
-v-strings are not completely supported in any version of Perl prior to
-5.8.1.
-
-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 Version Object Internals
-
-version.pm provides an overloaded version object that is designed to both
-encapsulate the author's intended $VERSION assignment as well as make it
-completely natural to use those objects as if they were numbers (e.g. for
-comparisons). To do this, a version object contains both the original
-representation as typed by the author, as well as a parsed representation
-to ease comparisons. Version objects employ L<overload> methods to
-simplify code that needs to compare, print, etc the objects.
-
-The internal structure of version objects is a blessed hash with several
-components:
-
- bless( {
- 'original' => 'v1.2.3_4',
- 'alpha' => 1,
- 'qv' => 1,
- 'version' => [
- 1,
- 2,
- 3,
- 4
- ]
- }, 'version' );
-
-=over 4
-
-=item original
-
-A faithful representation of the value used to initialize this version
-object. The only time this will not be precisely the same characters
-that exist in the source file is if a short dotted-decimal version like
-v1.2 was used (in which case it will contain 'v1.2'). This form is
-B<STRONGLY> discouraged, in that it will confuse you and your users.
-
-=item qv
-
-A boolean that denotes whether this is a decimal or dotted-decimal version.
-See L<version/is_qv()>.
-
-=item alpha
-
-A boolean that denotes whether this is an alpha version. NOTE: that the
-underscore can only appear in the last position. See L<version/is_alpha()>.
-
-=item version
-
-An array of non-negative integers that is used for comparison purposes with
-other version objects.
-
-=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 stringified form
-as a simple scalar (i.e. not an object), but the warning message generated
-includes either the stringified form or the normal form, depending on how
-it was called.
-
-For example:
-
- package Foo;
- $VERSION = 1.2;
-
- package Bar;
- $VERSION = "v1.3.5"; # 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 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 Decimal 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. 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 $module->VERSION;
-
-will also exclusively return the stringified form. See L</Stringification>
-for more details.
-
-=head1 USAGE DETAILS
-
-=head2 Using modules that use version.pm
-
-As much as possible, the version.pm module remains compatible with all
-current code. However, if your module is using a module that has defined
-C<$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; $VERSION = qv('1.2.2');
- ...module code here...
- 1;
-
-=over 4
-
-=item Decimal versions always work
-
-Code of the form:
-
- use Example 1.002003;
-
-will always work correctly. The C<use> will perform an automatic
-C<$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 Dotted-Decimal 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?> above). 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|UNIVERSAL/VERSION>. This is not true in Perl 5.005_04,
-however, so you are B<strongly encouraged> to always use a Decimal version
-in your code, even for those versions of Perl which support the Dotted-Decimal
-version.
-
-=back
-
-=head2 Object Methods
-
-=over 4
-
-=item new()
-
-Like many OO interfaces, the new() method is used to initialize version
-objects. If two arguments are passed to C<new()>, the B<second> one will be
-used as if it were prefixed with "v". This is to support historical use of the
-C<qw> operator with 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 $);
-
-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
-Decimal versions (i.e. 1.10 follows 1.9), so it must be handled as if
-it were a Dotted-Decimal 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(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();
-
-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
-
-=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); # v1.2.0
- $v2 = qv("1.2"); # also v1.2.0
-
-As you can see, either a bare number or a quoted string can usually
-be used interchangeably, 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.
-
-=back
-
-For the subsequent examples, the following three objects will be used:
-
- $ver = version->new("1.2.3.4"); # see "Quoting Rules"
- $alpha = version->new("1.2.3_4"); # see "Alpha Versions"
- $nver = version->new(1.002); # see "Decimal Versions"
-
-=over 4
-
-=item Normal Form
-
-For any version object which is initialized with multiple decimal
-places (either quoted or if possible v-string), or initialized using
-the L<qv()|version/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 v1.2.3.4
- print $ver->stringify; # ditto
- print $ver; # ditto
- print $nver->normal; # prints as v1.2.0
- print $nver->stringify; # prints as 1.002,
- # see "Stringification"
-
-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
- {...}
-
-=back
-
-=over 4
-
-=item Numification
-
-Although all mathematical operations on version objects are forbidden
-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 1.002003004
- print $nver->numify; # prints 1.002
-
-Unlike the stringification operator, there is never any need to append
-trailing zeros to preserve the correct version value.
-
-=back
-
-=over 4
-
-=item Stringification
-
-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.
-
-For example:
-
- 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
-
-See also L<UNIVERSAL::VERSION|UNIVERSAL/VERSION>, as this also returns the stringified form
-when used as a class method.
-
-IMPORTANT NOTE: There is one exceptional cases shown in the above table
-where the "initializer" is not stringwise equivalent to the stringified
-representation. If you use the C<qv>() operator on a version without a
-leading 'v' B<and> with only a single decimal place, the stringified output
-will have a leading 'v', to preserve the sense. See the L</qv()> operator
-for more details.
-
-IMPORTANT NOTE 2: Attempting to bypass the normal stringification rules by
-manually applying L<numify()|version/numify()> and L<normal()|version/normal()> will sometimes yield
-surprising results:
-
- print version->new(version->new("v1.0")->numify)->normal; # v1.0.0
-
-The reason for this is that the L<numify()|version/numify()> operator will turn "v1.0"
-into the equivalent string "1.000000". Forcing the outer version object
-to L<normal()|version/normal()> form will display the mathematically equivalent "v1.0.0".
-
-As the example in L</new()> shows, you can always create a copy of an
-existing version object with the same value by the very compact:
-
- $v2 = $v1->new($v1);
-
-and be assured that both C<$v1> and C<$v2> will be completely equivalent,
-down to the same internal representation as well as stringification.
-
-=back
-
-=over 4
-
-=item Comparison operators
-
-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
-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 == 1.2.3.4 $ver eq "1.2.3.4" see discussion below
-
-It is probably best to chose either the Decimal notation or the string
-notation and stick with it, to reduce confusion. Perl6 version objects
-B<may> only support Decimal comparisons. See also L<Quoting Rules>.
-
-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) > 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<Decimal Versions> or
-L<Dotted-Decimal Versions> with multiple decimal points.
-
-=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 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
-
-=head1 AUTHOR
-
-John Peacock E<lt>jpeacock@cpan.orgE<gt>
-
-=head1 SEE ALSO
-
-L<perl>.
-
-=cut
https://perl5.git.perl.org / perl5.git / blobdiff