SemVer(3) Use semantic version numbers


  use SemVer; our $VERSION = SemVer->new('1.2.0b1');


This module subclasses version to create semantic versions, as defined by the Semantic Versioning 1.0.0 Specification <>. The two salient points of the specification, for the purposes of version formatting, are:
A normal version number MUST take the form X.Y.Z where X, Y, and Z are integers. X is the major version, Y is the minor version, and Z is the patch version. Each element MUST increase numerically by increments of one. For instance: "1.9.0 < 1.10.0 < 1.11.0".
A pre-release version number MAY be denoted by appending an arbitrary string immediately following the patch version and a dash. The string MUST be comprised of only alphanumerics plus dash "[0-9A-Za-z-]". Pre-release versions satisfy but have a lower precedence than the associated normal version. Precedence SHOULD be determined by lexicographic ASCII sort order. For instance: "1.0.0-alpha1 < 1.0.0-beta1 < 1.0.0-beta2 < 1.0.0-rc1 < 1.0.0".


For strict parsing of semantic version numbers, use the "new()" constructor. If you need something more flexible, use "declare()". And if you need something more comparable with what version expects, try "parse()". Compare how these constructors deal with various version strings (with values shown as returned by "normal()":

    Argument  | new      | declare     | parse
  '1.0.0'     | 1.0.0    | 1.0.0       | 1.0.0
  '5.5.2-b1'  | 5.5.2-b1 | 5.5.2-b1    | 5.5.2-b1
  '1.05.0'    | <error>  | 1.5.0       | 1.5.0
  '1.0'       | <error>  | 1.0.0       | 1.0.0
  '  012.2.2' | <error>  | 12.2.2      | 12.2.2
  '1.1'       | <error>  | 1.1.0       | 1.100.0
   1.1        | <error>  | 1.1.0       | 1.100.0
  '1.1.0b1'   | <error>  | 1.1.0-b1    | 1.1.0-b1
  '1.1-b1'    | <error>  | 1.1.0-b1    | 1.100.0-b1
  '1.2.b1'    | <error>  | 1.2.0-b1    | 1.2.0-b1
  '9.0-beta4' | <error>  | 9.0.0-beta4 | 9.0.0-beta4
  '9'         | <error>  | 9.0.0       | 9.0.0
  '1-b'       | <error>  | 1.0.0-b     | 1.0.0-b
   0          | <error>  | 0.0.0       | 0.0.0
  '0-rc1'     | <error>  | 0.0.0-rc1   | 0.0.0-rc1
  '1.02_30'   | <error>  | 1.23.0      | 1.23.0
   1.02_30    | <error>  | 1.23.0      | 1.23.0

Note that, unlike in version, the "declare" and "parse" methods ignore underscores. That is, version strings with underscores are treated as decimal numbers. Hence, the last two examples yield exactly the same semantic versions.

As with version objects, the comparison and stringification operators are all overloaded, so that you can compare semantic versions. You can also compare semantic versions with version objects (but not the other way around, alas). Boolean operators are also overloaded, such that all semantic version objects except for those consisting only of zeros are considered true.




  my $semver = SemVer->new('1.2.2');

Performs a validating parse of the version string and returns a new semantic version object. If the version string does not adhere to the semantic version specification an exception will be thrown. See "declare" and "parse" for more forgiving constructors.


  my $semver = SemVer->declare('1.2'); # 1.2.0

This parser strips out any underscores from the version string and passes it to to "version"'s "declare" constructor, which always creates dotted-integer version objects. This is the most flexible way to declare versions. Consider using it to normalize version strings.


  my $semver = SemVer->parse('1.2'); # 1.200.0

This parser dispatches to "version"'s "parse" constructor, which tries to be more flexible in how it converts simple decimal strings and numbers. Not really recommended, since it's treatment of decimals is quite different from the dotted-integer format of semantic version strings, and thus can lead to inconsistencies. Included only for proper compatibility with version.

Instance Methods


  SemVer->declare('v1.2')->normal;       # 1.2.0
  SemVer->parse('1.2')->normal;          # 1.200.0
  SemVer->declare('1.02.0-b1')->normal;  # 1.2.0-b1
  SemVer->parse('1.02_30')->normal       # 1.230.0
  SemVer->parse(1.02_30)->normal         # 1.23.0

Returns a normalized representation of the version. This string will always be a strictly-valid dotted-integer semantic version string suitable for passing to "new()". Unlike version's "normal" method, there will be no leading ``v''.


  SemVer->declare('v1.2')->stringify;    # v1.2
  SemVer->parse('1.200')->stringify;     # v1.200
  SemVer->declare('1.2-r1')->stringify;  # v1.2-r1
  SemVer->parse(1.02_30)->stringify;     # v1.0230
  SemVer->parse(1.02_30)->stringify;     # v1.023

Returns a string that is as close to the original representation as possible. If the original representation was a numeric literal, it will be returned the way perl would normally represent it in a string. This method is used whenever a version object is interpolated into a string.


Throws an exception. Semantic versions cannot be numified. Just don't go there.


  my $is_alpha = $semver->is_alpha;

Returns true if an ASCII string is appended to the end of the version string. This also means that the version number is a ``special version'', in the semantic versioning specification meaning of the phrase.


Compares the semantic version object to another version object or string and returns 0 if they're the same, -1 if the invocant is smaller than the argument, and 1 if the invocant is greater than the argument.

Mostly you don't need to worry about this: Just use the comparison operators instead. They will use this method:

  if ($semver < $another_semver) {
      die "Need $another_semver or higher";

Note that in addition to comparing other semantic version objects, you can also compare regular version objects:

  if ($semver < $version) {
      die "Need $version or higher";

You can also pass in a version string. It will be turned into a semantic version object using "declare". So if you're using integer versions, you may or may not get what you want:

  my $semver  = version::Semver->new('1.2.0');
  my $version = '1.2';
  my $bool    = $semver == $version; # true

If that's not what you want, pass the string to "parse" first:

  my $semver  = version::Semver->new('1.2.0');
  my $version = version::Semver->parse('1.2'); # 1.200.0
  my $bool    = $semver == $version; # false

See Also


This module is managed in an open GitHub repository <>. Feel free to fork and contribute, or to clone <git://> and send patches!

Found a bug? Please post <> or email <mailto:[email protected]> a report!


Many thanks to version author John Peacock for his suggestions and debugging help.


David E. Wheeler <[email protected]>

Copyright and License

Copyright (c) 2010-2015 David E. Wheeler. Some Rights Reserved.

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