Class: Gem::Version

Inherits:
Object
  • Object
show all
Includes:
Comparable
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. 1.0

  2. 1.0.b1

  3. 1.0.a.2

  4. 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!).

  1. The change may be an implementation detail only and have no effect on the client software.

  2. The change may add new features, but do so in a way that client software written to an earlier version is still compatible.

  3. 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 use top to get the top of the stack).

  • Rename the methods to push_item and pop_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 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. 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   ... &infin;
"~> 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.

Constant Summary collapse

VERSION_PATTERN =

:nodoc:

'[0-9]+(?>\.[0-9a-zA-Z]+)*(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?'.freeze
ANCHORED_VERSION_PATTERN =

:nodoc:

/\A\s*(#{VERSION_PATTERN})?\s*\z/.freeze
Requirement =

This is needed for compatibility with older yaml gemspecs.

Gem::Requirement
@@all = 
{}
@@bump = 
{}
@@release = 
{}

Class Method Summary collapse

Instance Method Summary collapse

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.



215
216
217
218
219
220
221
222
223
224
225
 
# File 'lib/rubygems/version.rb', line 215

def initialize(version)
  unless self.class.correct?(version)
    raise ArgumentError, "Malformed version number string #{version}"
  end

  # If version is an empty string convert it to 0
  version = 0 if version.is_a?(String) && version =~ /\A\s*\Z/

  @version = version.to_s.strip.gsub("-",".pre.")
  @segments = nil
end

Class Method Details

.correct?(version) ⇒ Boolean

True if the version string matches RubyGems’ requirements.

Returns:

  • (Boolean) 


175
176
177
178
179
180
181
 
# File 'lib/rubygems/version.rb', line 175

def self.correct?(version)
  unless Gem::Deprecate.skip
    warn "nil versions are discouraged and will be deprecated in Rubygems 4" if version.nil?
  end

  !!(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



191
192
193
194
195
196
197
198
199
 
# File 'lib/rubygems/version.rb', line 191

def self.create(input)
  if self === input # check yourself before you wreck yourself
    input
  elsif input.nil?
    nil
  else
    new input
  end
end

.new(version) ⇒ Object

:nodoc:



205
206
207
208
209
 
# File 'lib/rubygems/version.rb', line 205

def self.new(version) # :nodoc:
  return super unless Gem::Version == self

  @@all[version] ||= super
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 or a valid version String return nil.



347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
 
# File 'lib/rubygems/version.rb', line 347

def <=>(other)
  return self <=> self.class.new(other) if (String === other) && self.class.correct?(other)

  return unless Gem::Version === other
  return 0 if @version == other._version || canonical_segments == other.canonical_segments

  lhsegments = canonical_segments
  rhsegments = other.canonical_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

#approximate_recommendation ⇒ Object

A recommended version for use with a ~> Requirement.



329
330
331
332
333
334
335
336
337
338
339
 
# File 'lib/rubygems/version.rb', line 329

def approximate_recommendation
  segments = self.segments

  segments.pop    while segments.any? {|s| String === s }
  segments.pop    while segments.size > 2
  segments.push 0 while segments.size < 2

  recommendation = "~> #{segments.join(".")}"
  recommendation += ".a" if prerelease?
  recommendation
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.



233
234
235
236
237
238
239
240
241
242
 
# File 'lib/rubygems/version.rb', line 233

def bump
  @@bump[self] ||= begin
                     segments = self.segments
                     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
end

#canonical_segments ⇒ Object 



376
377
378
379
380
381
 
# File 'lib/rubygems/version.rb', line 376

def canonical_segments
  @canonical_segments ||=
    _split_segments.map! do |segments|
      segments.reverse_each.drop_while {|s| s == 0 }.reverse
    end.reduce(&:concat)
end

#encode_with(coder) ⇒ Object

:nodoc:



290
291
292
 
# File 'lib/rubygems/version.rb', line 290

def encode_with(coder) # :nodoc:
  coder.add 'version', @version
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”.

Returns:

  • (Boolean) 


248
249
250
 
# File 'lib/rubygems/version.rb', line 248

def eql?(other)
  self.class === other and @version == other._version
end

#freeze ⇒ Object 



383
384
385
386
387
 
# File 'lib/rubygems/version.rb', line 383

def freeze
  prerelease?
  canonical_segments
  super
end

#hash ⇒ Object

:nodoc:



252
253
254
 
# File 'lib/rubygems/version.rb', line 252

def hash # :nodoc:
  canonical_segments.hash
end

#init_with(coder) ⇒ Object

:nodoc:



256
257
258
 
# File 'lib/rubygems/version.rb', line 256

def init_with(coder) # :nodoc:
  yaml_initialize coder.tag, coder.map
end

#inspect ⇒ Object

:nodoc:



260
261
262
 
# File 'lib/rubygems/version.rb', line 260

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.



268
269
270
 
# File 'lib/rubygems/version.rb', line 268

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.



276
277
278
 
# File 'lib/rubygems/version.rb', line 276

def marshal_load(array)
  initialize array[0]
end

#prerelease? ⇒ Boolean

A version is considered a prerelease if it contains a letter.

Returns:

  • (Boolean) 


297
298
299
300
301
302
 
# File 'lib/rubygems/version.rb', line 297

def prerelease?
  unless instance_variable_defined? :@prerelease
    @prerelease = !!(@version =~ /[a-zA-Z]/)
  end
  @prerelease
end

#pretty_print(q) ⇒ Object

:nodoc:



304
305
306
 
# File 'lib/rubygems/version.rb', line 304

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.



312
313
314
315
316
317
318
319
320
 
# File 'lib/rubygems/version.rb', line 312

def release
  @@release[self] ||= if prerelease?
    segments = self.segments
    segments.pop while segments.any? {|s| String === s }
    self.class.new segments.join('.')
  else
    self
  end
end

#segments ⇒ Object

:nodoc:



322
323
324
 
# File 'lib/rubygems/version.rb', line 322

def segments # :nodoc:
  _segments.dup
end

#to_yaml_properties ⇒ Object

:nodoc:



286
287
288
 
# File 'lib/rubygems/version.rb', line 286

def to_yaml_properties # :nodoc:
  ["@version"]
end

#version ⇒ Object Also known as: to_s

A string representation of this Version.



166
167
168
 
# File 'lib/rubygems/version.rb', line 166

def version
  @version.dup
end

#yaml_initialize(tag, map) ⇒ Object

:nodoc:



280
281
282
283
284
 
# File 'lib/rubygems/version.rb', line 280

def yaml_initialize(tag, map) # :nodoc:
  @version = map['version']
  @segments = nil
  @hash = nil
end