Class: Gem::Version
Relationships & Source Files | |
Super Chains via Extension / Inclusion / Inheritance | |
Instance Chain:
self,
Comparable
|
|
Inherits: | Object |
Defined in: | lib/rubygems/version.rb, lib/rubygems/requirement.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
If you want to specify a version restriction that includes both prereleases and regular releases of the 1.x series this is the best way:
s.add_dependency 'example', '>= 1.0.0.a', '< 2.0.0'
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, but as soon as they make 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. They write to the original interface (no top
), so their version constraint looks like:
gem 'stack', '>= 0.0'
Essentially, any version is OK with Client A. An incompatible change to the library will cause them grief, but they are willing to take the chance (we call Client A optimistic).
Client B is just like Client A except for two things: (1) They use the depth
method and (2) they are worried about future incompatibilities, so they write their 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 they are 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 an “approximate” 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
"~> 3" 3.0 ... 4.0
For the last example, single-digit versions are automatically extended with a zero to give a sensible result.
Class Method Summary
-
.correct?(version) ⇒ Boolean
True if the #version string matches RubyGems' requirements.
-
.create(input)
Factory method to create a
Version
object.
Instance Attribute Summary
-
#prerelease? ⇒ Boolean
readonly
A version is considered a prerelease if it contains a letter.
Instance Method Summary
-
#<=>(other)
Compares this version with
other
returning -1, 0, or 1 if the other version is larger, the same, or smaller than this one. -
#approximate_recommendation
A recommended version for use with a ~> Requirement.
-
#bump
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.
-
#initialize(version) ⇒ Version
constructor
Constructs a
Version
from the #version string. -
#marshal_dump
Dump only the raw version string, not the complete object.
-
#marshal_load(array)
Load custom marshal format.
-
#release
The release for this version (e.g. 1.2.0.a -> 1.2.0).
-
#to_s
Alias for #version.
-
#version
(also: #to_s)
A string representation of this
Version
. - #_version protected
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.
Class Method Details
.correct?(version) ⇒ Boolean
True if the #version string matches RubyGems' requirements.
# File 'lib/rubygems/version.rb', line 172
def self.correct? version version.to_s =~ ANCHORED_VERSION_PATTERN end
.create(input)
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
# File 'lib/rubygems/version.rb', line 184
def self.create input if self === input then # check yourself before you wreck yourself input elsif input.nil? then nil else new input end end
Instance Attribute Details
#prerelease? ⇒ Boolean
(readonly)
A version is considered a prerelease if it contains a letter.
# File 'lib/rubygems/version.rb', line 284
def prerelease? unless instance_variable_defined? :@prerelease @prerelease = !!(@version =~ /[a-zA-Z]/) end @prerelease end
Instance Method Details
#<=>(other)
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 Version
return nil
.
# File 'lib/rubygems/version.rb', line 338
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
#_version (protected)
[ GitHub ]# File 'lib/rubygems/version.rb', line 367
def _version @version end
#approximate_recommendation
A recommended version for use with a ~> Requirement.
#bump
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.
#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”.
# File 'lib/rubygems/version.rb', line 235
def eql? other self.class === other and @version == other._version end
#marshal_dump
Dump only the raw version string, not the complete object. It's a string for backwards (RubyGems 1.3.5 and earlier) compatibility.
# File 'lib/rubygems/version.rb', line 255
def marshal_dump [version] end
#marshal_load(array)
Load custom marshal format. It's a string for backwards (RubyGems 1.3.5 and earlier) compatibility.
# File 'lib/rubygems/version.rb', line 263
def marshal_load array initialize array[0] end
#release
The release for this version (e.g. 1.2.0.a -> 1.2.0). Non-prerelease versions return themselves.
#to_s
Alias for #version.
# File 'lib/rubygems/version.rb', line 167
alias to_s version
#version Also known as: #to_s
A string representation of this Version
.
# File 'lib/rubygems/version.rb', line 163
def version @version.dup end