如何写gem

如何写gem

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• ruby

gem 如何写gem 打包gem 如何打包gem 开发gem

第一步：用bundle gem gem_name生成基本结构，如下：

 [root@arch demo]$ bundle gem rename_url
       create  rename_url/Gemfile
       create  rename_url/Rakefile
       create  rename_url/.gitignore
       create  rename_url/rename_url.gemspec
       create  rename_url/lib/rename_url.rb
       create  rename_url/lib/rename_url/version.rb
 Initializating git repo in /home/suchj/programs/demo/rename_url

注：

Gemfile # 描述依赖

Rakefile # 发布和打包的 rake tasks

GEM_NAME.gemspec # gem 的 spec

GEM_NAME/lib/GEM_NAME.rb 与 GEM_NAME/lib/GEMNAME/ # gem 里的 library

GEM_NAME/lib/GEM_NAME/version.rb # 版本记录

第二步：写Gems规范文件，rename_url.gemspec

 # -*- encoding: utf-8 -*-
 $:.push File.expand_path("../lib", __FILE__)
 require "rename_url/version"

 Gem::Specification.new do |s|
   s.name        = "rename_url"
   s.version     = RenameUrl::VERSION
   s.authors     = ["xx"]
   s.email       = ["[email protected]"]
   s.homepage    = ""
   s.summary     = %q{TODO: Write a gem summary}
   s.description = %q{TODO: Write a gem description}

   s.rubyforge_project = "rename_url"

   s.files         = `git ls-files`.split("\n")
   s.test_files    = `git ls-files -- {test,spec,features}/*`.split("\n")
   s.executables   = `git ls-files -- bin/*`.split("\n").map{ |f| File.basename(f) }
   s.require_paths = ["lib"]

   # specify any dependencies here; for example:
   # s.add_development_dependency "rspec"
   # s.add_runtime_dependency "rest-client"
 end

 

第三步：写实现，lib/rename_url.rb

 require "rename_url/version"

 module RenameUrl
   def self.included(base)
     base.extend(ClassMethods)
   end

   module ClassMethods
     def urlize
       include RenameUrl::InstanceMethods
     end
   end

   module InstanceMethods
     def to_param
       "#{id}_#{title}"
     end
   end
 end

 ActiveRecord::Base.send(:include, RenameUrl) #在model中引入

 第四步：打包gem

 [root@arch rename_url]$ gem build rename_url.gemspec
 WARNING:  no homepage specified
   Successfully built RubyGem
   Name: rename_url
   Version: 0.0.1
   File: rename_url-0.0.1.gem

 注：如果规范文件有信息没写全，会有警告

第五步：使用，在项目的Gemfile中加入

 gem 'rename_url', :path => '~/programs/rename_url'

 注：gem文件在哪就写哪个路径

post.rb

 class Post < ActiveRecord::Base
   urlize #相当于include RenameUrl::InstanceMethods
 end

测试：

 [root@arch demo]$ rails c
 Loading development environment (Rails 3.0.4)
 1.8.7 :001 > Post
  => Post(id: integer, name: string, title: string, content: text, created_at: datetime, updated_at: datetime)
 1.8.7 :002 > Post.create(:title => "test")
  => #<Post id: 2, name: nil, title: "test", content: nil, created_at: "2012-02-03 08:38:53", updated_at: "2012-02-03 08:38:53">
 1.8.7 :003 > Post.find_by_title("test").to_param
  => "2_test"

 OK，打完收工