Class: Gem::Version
- Inherits:
-
Object
- Object
- Gem::Version
- Includes:
- Comparable
- Defined in:
- lib/rubygems/version.rb
Overview
The Version class processes string versions into comparable values. A version string should normally be a series of numbers separated by periods. Each part (digits separated by periods) is considered its own number, and these are used for sorting. So for instance, 3.10 sorts higher than 3.2 because ten is greater than two.
If any part contains letters (currently only a-z are supported) then that version is considered prerelease. Versions with a prerelease part in the Nth part sort less than versions with N-1 parts. Prerelease parts are sorted alphabetically using the normal Ruby string sorting rules. If a prerelease part contains both letters and numbers, it will be broken into multiple parts to provide expected sort behavior (1.0.a10 becomes 1.0.a.10, and is greater than 1.0.a9).
Prereleases sort between real releases (newest to oldest):
-
1.0
-
1.0.b1
-
1.0.a.2
-
0.9
How Software Changes
Users expect to be able to specify a version constraint that gives them some reasonable expectation that new versions of a library will work with their software if the version constraint is true, and not work with their software if the version constraint is false. In other words, the perfect system will accept all compatible versions of the library and reject all incompatible versions.
Libraries change in 3 ways (well, more than 3, but stay focused here!).
-
The change may be an implementation detail only and have no effect on the client software.
-
The change may add new features, but do so in a way that client software written to an earlier version is still compatible.
-
The change may change the public interface of the library in such a way that old software is no longer compatible.
Some examples are appropriate at this point. Suppose I have a Stack class that supports a push
and a pop
method.
Examples of Category 1 changes:
-
Switch from an array based implementation to a linked-list based implementation.
-
Provide an automatic (and transparent) backing store for large stacks.
Examples of Category 2 changes might be:
-
Add a
depth
method to return the current depth of the stack. -
Add a
top
method that returns the current top of stack (without changing the stack). -
Change
push
so that it returns the item pushed (previously it had no usable return value).
Examples of Category 3 changes might be:
-
Changes
pop
so that it no longer returns a value (you must usetop
to get the top of the stack). -
Rename the methods to
push_item
andpop_item
.
RubyGems Rational Versioning
-
Versions shall be represented by three non-negative integers, separated by periods (e.g. 3.1.4). The first integers is the “major” version number, the second integer is the “minor” version number, and the third integer is the “build” number.
-
A category 1 change (implementation detail) will increment the build number.
-
A category 2 change (backwards compatible) will increment the minor version number and reset the build number.
-
A category 3 change (incompatible) will increment the major build number and reset the minor and build numbers.
-
Any “public” release of a gem should have a different version. Normally that means incrementing the build number. This means a developer can generate builds all day long for himself, but as soon as he/she makes a public release, the version must be updated.
Examples
Let’s work through a project lifecycle using our Stack example from above.
- Version 0.0.1
-
The initial Stack class is release.
- Version 0.0.2
-
Switched to a linked=list implementation because it is cooler.
- Version 0.1.0
-
Added a
depth
method. - Version 1.0.0
-
Added
top
and madepop
return nil (pop
used to return the old top item). - Version 1.1.0
-
push
now returns the value pushed (it used it return nil). - Version 1.1.1
-
Fixed a bug in the linked list implementation.
- Version 1.1.2
-
Fixed a bug introduced in the last fix.
Client A needs a stack with basic push/pop capability. He writes to the original interface (no top
), so his version constraint looks like:
gem 'stack', '~> 0.0'
Essentially, any version is OK with Client A. An incompatible change to the library will cause him grief, but he is willing to take the chance (we call Client A optimistic).
Client B is just like Client A except for two things: (1) He uses the depth
method and (2) he is worried about future incompatibilities, so he writes his version constraint like this:
gem 'stack', '~> 0.1'
The depth
method was introduced in version 0.1.0, so that version or anything later is fine, as long as the version stays below version 1.0 where incompatibilities are introduced. We call Client B pessimistic because he is worried about incompatible future changes (it is OK to be pessimistic!).
Preventing Version Catastrophe:
From: blog.zenspider.com/2008/10/rubygems-howto-preventing-cata.html
Let’s say you’re depending on the fnord gem version 2.y.z. If you specify your dependency as “>= 2.0.0” then, you’re good, right? What happens if fnord 3.0 comes out and it isn’t backwards compatible with 2.y.z? Your stuff will break as a result of using “>=”. The better route is to specify your dependency with a “spermy” version specifier. They’re a tad confusing, so here is how the dependency specifiers work:
Specification From ... To (exclusive)
">= 3.0" 3.0 ... ∞
"~> 3.0" 3.0 ... 4.0
"~> 3.0.0" 3.0.0 ... 3.1
"~> 3.5" 3.5 ... 4.0
"~> 3.5.0" 3.5.0 ... 3.6
Constant Summary collapse
- VERSION_PATTERN =
:nodoc:
'[0-9]+(?>\.[0-9a-zA-Z]+)*'
- ANCHORED_VERSION_PATTERN =
:nodoc:
/\A\s*(#{VERSION_PATTERN})?\s*\z/
- Requirement =
:stopdoc: Gem::Version::Requirement is used in a lot of old YAML specs. It’s aliased here for backwards compatibility. I’d like to remove this, maybe in RubyGems 2.0.
::Gem::Requirement
Instance Attribute Summary collapse
-
#version ⇒ Object
(also: #to_s)
readonly
A string representation of this Version.
Class Method Summary collapse
-
.correct?(version) ⇒ Boolean
True if the
version
string matches RubyGems’ requirements. -
.create(input) ⇒ Object
Factory method to create a Version object.
Instance Method Summary collapse
-
#<=>(other) ⇒ Object
Compares this version with
other
returning -1, 0, or 1 if the other version is larger, the same, or smaller than this one. -
#bump ⇒ Object
Return a new version object where the next to the last revision number is one greater (e.g., 5.3.1 => 5.4).
-
#eql?(other) ⇒ Boolean
A Version is only eql? to another version if it’s specified to the same precision.
-
#hash ⇒ Object
:nodoc:.
-
#init_with(coder) ⇒ Object
:nodoc:.
-
#initialize(version) ⇒ Version
constructor
Constructs a Version from the
version
string. -
#inspect ⇒ Object
:nodoc:.
-
#marshal_dump ⇒ Object
Dump only the raw version string, not the complete object.
-
#marshal_load(array) ⇒ Object
Load custom marshal format.
-
#prerelease? ⇒ Boolean
A version is considered a prerelease if it contains a letter.
-
#pretty_print(q) ⇒ Object
:nodoc:.
-
#release ⇒ Object
The release for this version (e.g. 1.2.0.a -> 1.2.0).
-
#segments ⇒ Object
:nodoc:.
-
#spermy_recommendation ⇒ Object
A recommended version for use with a ~> Requirement.
- #yaml_initialize(tag, map) ⇒ Object
Constructor Details
#initialize(version) ⇒ Version
Constructs a Version from the version
string. A version string is a series of digits or ASCII letters separated by dots.
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# File 'lib/rubygems/version.rb', line 186 def initialize version raise ArgumentError, "Malformed version number string #{version}" unless self.class.correct?(version) @version = version.to_s.dup @version.strip! end |
Instance Attribute Details
#version ⇒ Object (readonly) Also known as: to_s
A string representation of this Version.
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# File 'lib/rubygems/version.rb', line 154 def version @version end |
Class Method Details
.correct?(version) ⇒ Boolean
True if the version
string matches RubyGems’ requirements.
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# File 'lib/rubygems/version.rb', line 160 def self.correct? version version.to_s =~ ANCHORED_VERSION_PATTERN end |
.create(input) ⇒ Object
Factory method to create a Version object. Input may be a Version or a String. Intended to simplify client code.
ver1 = Version.create('1.3.17') # -> (Version object)
ver2 = Version.create(ver1) # -> (ver1)
ver3 = Version.create(nil) # -> nil
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# File 'lib/rubygems/version.rb', line 172 def self.create input if input.respond_to? :version then input elsif input.nil? then nil else new input end end |
Instance Method Details
#<=>(other) ⇒ Object
Compares this version with other
returning -1, 0, or 1 if the other version is larger, the same, or smaller than this one. Attempts to compare to something that’s not a Gem::Version
return nil
.
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# File 'lib/rubygems/version.rb', line 303 def <=> other return unless Gem::Version === other return 0 if @version == other.version lhsegments = segments rhsegments = other.segments lhsize = lhsegments.size rhsize = rhsegments.size limit = (lhsize > rhsize ? lhsize : rhsize) - 1 i = 0 while i <= limit lhs, rhs = lhsegments[i] || 0, rhsegments[i] || 0 i += 1 next if lhs == rhs return -1 if String === lhs && Numeric === rhs return 1 if Numeric === lhs && String === rhs return lhs <=> rhs end return 0 end |
#bump ⇒ Object
Return a new version object where the next to the last revision number is one greater (e.g., 5.3.1 => 5.4).
Pre-release (alpha) parts, e.g, 5.3.1.b.2 => 5.4, are ignored.
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# File 'lib/rubygems/version.rb', line 200 def bump segments = self.segments.dup segments.pop while segments.any? { |s| String === s } segments.pop if segments.size > 1 segments[-1] = segments[-1].succ self.class.new segments.join(".") end |
#eql?(other) ⇒ Boolean
A Version is only eql? to another version if it’s specified to the same precision. Version “1.0” is not the same as version “1”.
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# File 'lib/rubygems/version.rb', line 213 def eql? other self.class === other and @version == other.version end |
#hash ⇒ Object
:nodoc:
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# File 'lib/rubygems/version.rb', line 217 def hash # :nodoc: @hash ||= segments.hash end |
#init_with(coder) ⇒ Object
:nodoc:
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# File 'lib/rubygems/version.rb', line 221 def init_with coder # :nodoc: yaml_initialize coder.tag, coder.map end |
#inspect ⇒ Object
:nodoc:
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# File 'lib/rubygems/version.rb', line 225 def inspect # :nodoc: "#<#{self.class} #{version.inspect}>" end |
#marshal_dump ⇒ Object
Dump only the raw version string, not the complete object. It’s a string for backwards (RubyGems 1.3.5 and earlier) compatibility.
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# File 'lib/rubygems/version.rb', line 233 def marshal_dump [version] end |
#marshal_load(array) ⇒ Object
Load custom marshal format. It’s a string for backwards (RubyGems 1.3.5 and earlier) compatibility.
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# File 'lib/rubygems/version.rb', line 241 def marshal_load array initialize array[0] end |
#prerelease? ⇒ Boolean
A version is considered a prerelease if it contains a letter.
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# File 'lib/rubygems/version.rb', line 254 def prerelease? @prerelease ||= @version =~ /[a-zA-Z]/ end |
#pretty_print(q) ⇒ Object
:nodoc:
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# File 'lib/rubygems/version.rb', line 258 def pretty_print q # :nodoc: q.text "Gem::Version.new(#{version.inspect})" end |
#release ⇒ Object
The release for this version (e.g. 1.2.0.a -> 1.2.0). Non-prerelease versions return themselves.
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# File 'lib/rubygems/version.rb', line 266 def release return self unless prerelease? segments = self.segments.dup segments.pop while segments.any? { |s| String === s } self.class.new segments.join('.') end |
#segments ⇒ Object
:nodoc:
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# File 'lib/rubygems/version.rb', line 274 def segments # :nodoc: # segments is lazy so it can pick up version values that come from # old marshaled versions, which don't go through marshal_load. @segments ||= @version.scan(/[0-9]+|[a-z]+/i).map do |s| /^\d+$/ =~ s ? s.to_i : s end end |
#spermy_recommendation ⇒ Object
A recommended version for use with a ~> Requirement.
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# File 'lib/rubygems/version.rb', line 287 def spermy_recommendation segments = self.segments.dup segments.pop while segments.any? { |s| String === s } segments.pop while segments.size > 2 segments.push 0 while segments.size < 2 "~> #{segments.join(".")}" end |
#yaml_initialize(tag, map) ⇒ Object
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# File 'lib/rubygems/version.rb', line 245 def yaml_initialize(tag, map) @version = map['version'] @segments = nil @hash = nil end |