$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
+ $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<Extended 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>.
=head2 Numeric Versions
purposes of comparison with other version objects. For example:
# 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( 1.2); # 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); # 1.002300 v1.2.300
- $v = version->new( 1.00203); # 1.002030 v1.2.30
+ $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
# 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("v1.2.3"); # v1.2.3
$v = qv("1.2.3"); # v1.2.3
$v = qv("1.20"); # v1.20.0
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
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 $v1.
=back
=item * Stringification
-In order to mirror as much as possible the existing behavior of ordinary
-$VERSION scalars, the stringification operation will display differently,
-depending on whether the version was initialized as a L<Numeric Version>
-or L<Extended 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
-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.
+For example:
-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>.
+ 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 v1.2.3.4
- 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
$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.
+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 point will be treated exactly as if
-they were L<Numeric Versions>, for parsing purposes. The stringification for
-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.
+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.
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
$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
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