Class | Gem::Version |
In: |
lib/rubygems/version.rb
|
Parent: | Object |
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):
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!).
Some examples are appropriate at this point. Suppose I have a Stack class that supports a push and a pop method.
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 made pop 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!).
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
version | -> | to_s |
version | [R] | A string representation of this Version. |
True if the version string matches RubyGems’ requirements.
# File lib/rubygems/version.rb, line 159 159: def self.correct? version 160: version.to_s =~ ANCHORED_VERSION_PATTERN 161: end
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 171 171: def self.create input 172: if input.respond_to? :version then 173: input 174: elsif input.nil? then 175: nil 176: else 177: new input 178: end 179: end
Constructs a Version from the version string. A version string is a series of digits or ASCII letters separated by dots.
# File lib/rubygems/version.rb, line 185 185: def initialize version 186: raise ArgumentError, "Malformed version number string #{version}" unless 187: self.class.correct?(version) 188: 189: @version = version.to_s 190: @version.strip! 191: end
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.
# File lib/rubygems/version.rb, line 292 292: def <=> other 293: return unless Gem::Version === other 294: return 0 if @version == other.version 295: 296: lhsegments = segments 297: rhsegments = other.segments 298: 299: lhsize = lhsegments.size 300: rhsize = rhsegments.size 301: limit = (lhsize > rhsize ? lhsize : rhsize) - 1 302: 303: i = 0 304: 305: while i <= limit 306: lhs, rhs = lhsegments[i] || 0, rhsegments[i] || 0 307: i += 1 308: 309: next if lhs == rhs 310: return -1 if String === lhs && Numeric === rhs 311: return 1 if Numeric === lhs && String === rhs 312: 313: return lhs <=> rhs 314: end 315: 316: return 0 317: end
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.
# File lib/rubygems/version.rb, line 199 199: def bump 200: segments = self.segments.dup 201: segments.pop while segments.any? { |s| String === s } 202: segments.pop if segments.size > 1 203: 204: segments[-1] = segments[-1].succ 205: self.class.new segments.join(".") 206: end
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 228 228: def marshal_dump 229: [version] 230: end
Load custom marshal format. It‘s a string for backwards (RubyGems 1.3.5 and earlier) compatibility.
# File lib/rubygems/version.rb, line 236 236: def marshal_load array 237: initialize array[0] 238: end
A version is considered a prerelease if it contains a letter.
# File lib/rubygems/version.rb, line 243 243: def prerelease? 244: @prerelease ||= @version =~ /[a-zA-Z]/ 245: end
The release for this version (e.g. 1.2.0.a -> 1.2.0). Non-prerelease versions return themselves.
# File lib/rubygems/version.rb, line 255 255: def release 256: return self unless prerelease? 257: 258: segments = self.segments.dup 259: segments.pop while segments.any? { |s| String === s } 260: self.class.new segments.join('.') 261: end
A recommended version for use with a ~> Requirement.
# File lib/rubygems/version.rb, line 276 276: def spermy_recommendation 277: segments = self.segments.dup 278: 279: segments.pop while segments.any? { |s| String === s } 280: segments.pop while segments.size > 2 281: segments.push 0 while segments.size < 2 282: 283: "~> #{segments.join(".")}" 284: end