blocks|key|265161|text|我相信，不同的是，可挂载的应用程序与主机应用程序是隔离的，因此它们不能共享类-模型、助手等。这是因为可挂载的应用程序是Rack端点(即Rack应用程序本身)。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|265162|免责声明:像大多数人一样，我才刚刚开始使用Rails+3.1。|265163|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

The difference, I believe, is that a mountable app's are isolated from the host app, so they can't share classes - models, helper etc. This is because a Mountable app is a Rack endpoint (i.e a Rack app in its own right).

Disclaimer: I have, like most, only just started toying with Rails 3.1.

blocks|key|2963960|text|我的理解是，引擎就像插件一样，为现有的应用程序增加了功能。而可安装的应用程序本质上是一个应用程序，可以是独立的。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2963961|因此，如果您希望能够单独运行它或在另一个应用程序中运行它，您可以制作一个可挂载的应用程序。如果您打算将其添加到现有应用程序中，而不是单独运行，则可以使其成为引擎。|2963962|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

My understanding of the difference is that engines are like plugins, and add functionality to existing applications. While mountable apps are essentially an application, and can stand alone.

So if you want to be able to run it by itself or within another application you would make a mountable app. If you intend for it to be an addition to existing applications, but not run by itself you would make it an engine.

blocks|key|270738|text|我注意到以下几点：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|270739|全引擎|offset|length|style|BOLD|270740|使用完整的引擎时，父应用程序会从引擎继承路由。没有必要在parent_app/config/routes.rb中指定任何内容。在Gemfile中指定gem就足以让父应用程序继承模型、路由等。引擎路由指定为：|CODE|270741|#+my_engine/config/routes.rb+
Rails.application.routes.draw+do+
++#+whatever+
end+|code-block|syntax|javascript|270742|没有模型、控制器等的命名空间。父应用程序可以立即访问这些。|270743|可安装引擎|270744|默认情况下，引擎的命名空间是隔离的：|270745|#+my_engine/lib/my_engine/engine.rb
module+MyEngine+
++class+Engine+<+Rails::Engine+
++++isolate_namespace+MyEngine+
++end+
end|270746|使用可挂载的引擎，路由是命名空间的，父应用程序可以将此功能捆绑在单个路由下：|270747|#+my_engine/config/routes.rb+
MyEngine::Engine.routes.draw+do+
++#whatever+
end+

#+parent_app/config/routes.rb+
ParentApp::Application.routes.draw+do+
++++mount+MyEngine::Engine+=>+"/engine",+:as+=>+"namespaced"+
end+|270748|模型、控制器等与父应用程序隔离--尽管帮助程序可以很容易地共享。|270749|这些是我发现的主要区别。也许还有其他的？我已经在here上询问过了，但还没有收到回复。|270750|我的印象是，由于完整的引擎不会将自己与父应用程序隔离开来，因此最好将其用作与父应用程序相邻的独立应用程序。我相信名称冲突可能会发生。|270751|在您希望避免名称冲突并将引擎捆绑在父应用程序中的一个特定路由下的情况下，可以使用可安装的引擎。例如，我正在构建我的第一个为客户服务而设计的引擎。父应用程序可以将其功能捆绑在单个路由下，例如：|270752|mount+Cornerstone::Engine+=>+"/cornerstone",+:as+=>+"help"+|270753|如果我偏离了我的假设，请有人告诉我，我会解决这个问题。我写了一篇关于here干杯主题的小文章！|270754|entityMap|0|LINK|mutability|MUTABLE|url|http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/6a4691f62d0f1420|1|http://www.astjohn.ca/2011/08/06/rails-31-engines-mountable-or-full-part-1/^0|0|0|3|0|S|R|0|0|0|0|5|0|0|0|0|0|0|O|4|0|0|0|0|0|Y|4|1|0^^$0|@$1|2|3|4|5|6|7|1N|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1O|8|@$D|1P|E|1Q|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|1R|8|@$D|1S|E|1T|F|J]]|9|@]|A|$]]|$1|K|3|L|5|M|7|1U|8|@]|9|@]|A|$N|O]]|$1|P|3|Q|5|6|7|1V|8|@]|9|@]|A|$]]|$1|R|3|S|5|6|7|1W|8|@$D|1X|E|1Y|F|G]]|9|@]|A|$]]|$1|T|3|U|5|6|7|1Z|8|@]|9|@]|A|$]]|$1|V|3|W|5|M|7|20|8|@]|9|@]|A|$N|O]]|$1|X|3|Y|5|6|7|21|8|@]|9|@]|A|$]]|$1|Z|3|10|5|M|7|22|8|@]|9|@]|A|$N|O]]|$1|11|3|12|5|6|7|23|8|@]|9|@]|A|$]]|$1|13|3|14|5|6|7|24|8|@]|9|@$D|25|E|26|1|27]]|A|$]]|$1|15|3|16|5|6|7|28|8|@]|9|@]|A|$]]|$1|17|3|18|5|6|7|29|8|@]|9|@]|A|$]]|$1|19|3|1A|5|M|7|2A|8|@]|9|@]|A|$N|O]]|$1|1B|3|1C|5|6|7|2B|8|@]|9|@$D|2C|E|2D|1|2E]]|A|$]]|$1|1D|3|-4|5|6|7|2F|8|@]|9|@]|A|$]]]|1E|$1F|$5|1G|1H|1I|A|$1J|1K]]|1L|$5|1G|1H|1I|A|$1J|1M]]]]

I have noticed the following: 

Full Engine

With a full engine, the parent application inherits the routes from the engine. It is not necessary to specify anything in <code>parent_app/config/routes.rb</code>. Specifying the gem in Gemfile is enough for the parent app to inherit the models, routes etc. The engine routes are specified as: 

<pre><code># my_engine/config/routes.rb 
Rails.application.routes.draw do 
 # whatever 
end 
</code></pre>

No namespacing of models, controllers, etc. These are immediately 
accessible to the parent application. 

Mountable Engine

The engine's namespace is isolated by default:

<pre><code># my_engine/lib/my_engine/engine.rb
module MyEngine 
 class Engine &lt; Rails::Engine 
 isolate_namespace MyEngine 
 end 
end
</code></pre>

With a mountable engine, the routes are namespaced and the parent app can bundle this functionality under a single route: 

<pre><code># my_engine/config/routes.rb 
MyEngine::Engine.routes.draw do 
 #whatever 
end 

# parent_app/config/routes.rb 
ParentApp::Application.routes.draw do 
 mount MyEngine::Engine =&gt; "/engine", :as =&gt; "namespaced" 
end 
</code></pre>

Models, controllers, etc are isolated from the parent application - although helpers can be shared easily. 

These are the main differences I have spotted. Perhaps there are others? I have asked over <a href="http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/6a4691f62d0f1420">here</a>, but have yet to receive a response.

My impression is that since a full engine does not isolate itself from the parent application, it is best used as a standalone application adjacent to the parent app. I believe name clashes could occur.

A mountable engine could be used in situations where you want to avoid name conflicts and bundle the engine under one specific route in the parent application. For example, I am working on building my first engine designed for customer service. The parent application could bundle it's functionality under a single route such as:

<pre><code>mount Cornerstone::Engine =&gt; "/cornerstone", :as =&gt; "help" 
</code></pre>

If I'm way off in my assumptions, someone please let me know and I'll fix this response. I have made a small article about the subject <a href="http://www.astjohn.ca/2011/08/06/rails-31-engines-mountable-or-full-part-1/">here</a> Cheers!

blocks|key|265207|text|我也是这样想的，所以最终来到了这里。在我看来，前面的答案基本上涵盖了这个问题，但我认为下面的答案可能也会有所帮助：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|265208|#+generate+plugins+(NOTE:+using+same+name+each+time+to+minimize+differences)
#+-----------------------------------------------------------------------------

$+rails+plugin+new+test-plugin+-T
$+mv+test-plugin{,.01}

$+rails+plugin+new+test-plugin+-T+--mountable
$+mv+test-plugin{,.02}

$+rails+plugin+new+test-plugin+-T+--full
$+mv+test-plugin{,.03}

$+rails+plugin+new+test-plugin+-T+--full+--mountable
$+mv+test-plugin{,.04}




#+compare+"stock"+(01)+with+"mountable"+(02)
#+-----------------------------------------------------------------------------

$+diff+-r+test-plugin.01+test-plugin.02

Only+in+test-plugin.02:+app
Only+in+test-plugin.02:+config
Only+in+test-plugin.02/lib/test-plugin:+engine.rb
diff+-r+test-plugin.01/lib/test-plugin.rb+test-plugin.02/lib/test-plugin.rb
0a1,2
>+require+"test-plugin/engine"
>+
Only+in+test-plugin.02:+script
diff+-r+test-plugin.01/test-plugin.gemspec+test-plugin.02/test-plugin.gemspec
18a19
>+++#+s.add_dependency+"jquery-rails"




#+compare+"stock"+(01)+with+"full"+(03)
#+-----------------------------------------------------------------------------

$+diff+-r+test-plugin.01+test-plugin.03
Only+in+test-plugin.03:+app
Only+in+test-plugin.03:+config
Only+in+test-plugin.03/lib/test-plugin:+engine.rb
diff+-r+test-plugin.01/lib/test-plugin.rb+test-plugin.03/lib/test-plugin.rb
0a1,2
>+require+"test-plugin/engine"
>+
Only+in+test-plugin.03:+script
diff+-r+test-plugin.01/test-plugin.gemspec+test-plugin.03/test-plugin.gemspec
18a19
>+++#+s.add_dependency+"jquery-rails"




#+compare+"mountable"+(02)+with+"full"+(03)
#+-----------------------------------------------------------------------------

$+diff+-r+test-plugin.02+test-plugin.03

Only+in+test-plugin.03/app/assets/javascripts/test-plugin:+.gitkeep
Only+in+test-plugin.02/app/assets/javascripts/test-plugin:+application.js
Only+in+test-plugin.03/app/assets/stylesheets/test-plugin:+.gitkeep
Only+in+test-plugin.02/app/assets/stylesheets/test-plugin:+application.css
Only+in+test-plugin.03/app/controllers:+.gitkeep
Only+in+test-plugin.02/app/controllers:+test-plugin
Only+in+test-plugin.03/app/helpers:+.gitkeep
Only+in+test-plugin.02/app/helpers:+test-plugin
Only+in+test-plugin.03/app/mailers:+.gitkeep
Only+in+test-plugin.03/app/models:+.gitkeep
Only+in+test-plugin.03/app/views:+.gitkeep
Only+in+test-plugin.02/app/views:+layouts
diff+-r+test-plugin.02/config/routes.rb+test-plugin.03/config/routes.rb
1c1
<+TestPlugin::Engine.routes.draw+do
---
>+Rails.application.routes.draw+do
diff+-r+test-plugin.02/lib/test-plugin/engine.rb+test-plugin.03/lib/test-plugin/engine.rb
3d2
<+++++isolate_namespace+TestPlugin




#+compare+"mountable"+(02)+with+"full+&+mountable"+(04)
#+-----------------------------------------------------------------------------

$+diff+-r+test-plugin.02+test-plugin.04

<no+difference>




#+compare+"full"+(03)+with+"full+&+mountable"+(04)
#+-----------------------------------------------------------------------------

$+diff+-r+test-plugin.03+test-plugin.04

Only+in+test-plugin.03/app/assets/javascripts/test-plugin:+.gitkeep
Only+in+test-plugin.04/app/assets/javascripts/test-plugin:+application.js
Only+in+test-plugin.03/app/assets/stylesheets/test-plugin:+.gitkeep
Only+in+test-plugin.04/app/assets/stylesheets/test-plugin:+application.css
Only+in+test-plugin.03/app/controllers:+.gitkeep
Only+in+test-plugin.04/app/controllers:+test-plugin
Only+in+test-plugin.03/app/helpers:+.gitkeep
Only+in+test-plugin.04/app/helpers:+test-plugin
Only+in+test-plugin.03/app/mailers:+.gitkeep
Only+in+test-plugin.03/app/models:+.gitkeep
Only+in+test-plugin.03/app/views:+.gitkeep
Only+in+test-plugin.04/app/views:+layouts
diff+-r+test-plugin.03/config/routes.rb+test-plugin.04/config/routes.rb
1c1
<+Rails.application.routes.draw+do
---
>+TestPlugin::Engine.routes.draw+do
diff+-r+test-plugin.03/lib/test-plugin/engine.rb+test-plugin.04/lib/test-plugin/engine.rb
2a3
>+++++isolate_namespace+TestPlugin|code-block|syntax|javascript|265209|(对我来说)特别有趣的是，这两者之间没有区别|265210|rails+plugin+new+test-plugin+-T+--mountable|265211|和|265212|rails+plugin+new+test-plugin+-T+--full+--mountable|265213|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|U|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

i was wondering the same and, hence, ended up here. it seems to me that the earlier answers basically cover the question, but i thought the following might help as well:

<pre><code># generate plugins (NOTE: using same name each time to minimize differences)
# -----------------------------------------------------------------------------

$ rails plugin new test-plugin -T
$ mv test-plugin{,.01}

$ rails plugin new test-plugin -T --mountable
$ mv test-plugin{,.02}

$ rails plugin new test-plugin -T --full
$ mv test-plugin{,.03}

$ rails plugin new test-plugin -T --full --mountable
$ mv test-plugin{,.04}




# compare "stock" (01) with "mountable" (02)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.01 test-plugin.02

Only in test-plugin.02: app
Only in test-plugin.02: config
Only in test-plugin.02/lib/test-plugin: engine.rb
diff -r test-plugin.01/lib/test-plugin.rb test-plugin.02/lib/test-plugin.rb
0a1,2
&gt; require "test-plugin/engine"
&gt; 
Only in test-plugin.02: script
diff -r test-plugin.01/test-plugin.gemspec test-plugin.02/test-plugin.gemspec
18a19
&gt; # s.add_dependency "jquery-rails"




# compare "stock" (01) with "full" (03)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.01 test-plugin.03
Only in test-plugin.03: app
Only in test-plugin.03: config
Only in test-plugin.03/lib/test-plugin: engine.rb
diff -r test-plugin.01/lib/test-plugin.rb test-plugin.03/lib/test-plugin.rb
0a1,2
&gt; require "test-plugin/engine"
&gt; 
Only in test-plugin.03: script
diff -r test-plugin.01/test-plugin.gemspec test-plugin.03/test-plugin.gemspec
18a19
&gt; # s.add_dependency "jquery-rails"




# compare "mountable" (02) with "full" (03)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.02 test-plugin.03

Only in test-plugin.03/app/assets/javascripts/test-plugin: .gitkeep
Only in test-plugin.02/app/assets/javascripts/test-plugin: application.js
Only in test-plugin.03/app/assets/stylesheets/test-plugin: .gitkeep
Only in test-plugin.02/app/assets/stylesheets/test-plugin: application.css
Only in test-plugin.03/app/controllers: .gitkeep
Only in test-plugin.02/app/controllers: test-plugin
Only in test-plugin.03/app/helpers: .gitkeep
Only in test-plugin.02/app/helpers: test-plugin
Only in test-plugin.03/app/mailers: .gitkeep
Only in test-plugin.03/app/models: .gitkeep
Only in test-plugin.03/app/views: .gitkeep
Only in test-plugin.02/app/views: layouts
diff -r test-plugin.02/config/routes.rb test-plugin.03/config/routes.rb
1c1
&lt; TestPlugin::Engine.routes.draw do
---
&gt; Rails.application.routes.draw do
diff -r test-plugin.02/lib/test-plugin/engine.rb test-plugin.03/lib/test-plugin/engine.rb
3d2
&lt; isolate_namespace TestPlugin




# compare "mountable" (02) with "full &amp; mountable" (04)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.02 test-plugin.04

&lt;no difference&gt;




# compare "full" (03) with "full &amp; mountable" (04)
# -----------------------------------------------------------------------------

$ diff -r test-plugin.03 test-plugin.04

Only in test-plugin.03/app/assets/javascripts/test-plugin: .gitkeep
Only in test-plugin.04/app/assets/javascripts/test-plugin: application.js
Only in test-plugin.03/app/assets/stylesheets/test-plugin: .gitkeep
Only in test-plugin.04/app/assets/stylesheets/test-plugin: application.css
Only in test-plugin.03/app/controllers: .gitkeep
Only in test-plugin.04/app/controllers: test-plugin
Only in test-plugin.03/app/helpers: .gitkeep
Only in test-plugin.04/app/helpers: test-plugin
Only in test-plugin.03/app/mailers: .gitkeep
Only in test-plugin.03/app/models: .gitkeep
Only in test-plugin.03/app/views: .gitkeep
Only in test-plugin.04/app/views: layouts
diff -r test-plugin.03/config/routes.rb test-plugin.04/config/routes.rb
1c1
&lt; Rails.application.routes.draw do
---
&gt; TestPlugin::Engine.routes.draw do
diff -r test-plugin.03/lib/test-plugin/engine.rb test-plugin.04/lib/test-plugin/engine.rb
2a3
&gt; isolate_namespace TestPlugin
</code></pre>

of particular interest (to me) is the fact that there is no difference between

<pre><code>rails plugin new test-plugin -T --mountable
</code></pre>

and

<pre><code>rails plugin new test-plugin -T --full --mountable
</code></pre>

blocks|key|270785|text|这两个选项都将生成engine。不同之处在于，--mountable将在一个独立的名称空间中创建引擎，而--full将创建一个共享主应用程序名称空间的引擎。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|270786|这些差异将通过三种方式表现出来：|270787|1)引擎类文件将调用+isolate_namespace**:**|BOLD|270788|lib/my_full_engine/engine.rb:|270789|module+MyFullEngine
++class+Engine+<+Rails::Engine
++end
end|code-block|syntax|javascript|270790|lib/my_mountable_engine/engine.rb:|270791|module+MyMountableEngine
++class+Engine+<+Rails::Engine
++++isolate_namespace+MyMountableEngine+#+--mountable+option+inserted+this+line
++end
end|270792|2)引擎的+config/routes.rb+文件将命名为：|270793|全引擎：|270794|Rails.application.routes.draw+do
end|270795|挂载引擎：|270796|MyMountableEngine::Engine.routes.draw+do
end|270797|3)控制器、帮助器、视图和资产的文件结构将被命名为：|270798|270799|创建app/controllers/my_mountable_engine/application_controller.rb|blockquote|270800|270801|创建app/helpers/my_mountable_engine/application_helper.rb|270802|创建应用程序/邮件程序创建应用程序/模型|270803|创建app/views/layouts/my_mountable_engine/application.html.erb|270804|创建app/assets/images/my_mountable_engine|270805|创建app/assets/stylesheets/my_mountable_engine/application.css|270806|创建app/assets/javascripts/my_mountable_engine/application.js|270807|create+config/routes.rb+create+lib/my_my_Engine.rb|270808|创建lib/task/my_my_Engine.rake|270809|创建lib/my_my_engine/version.rb|270810|创建lib/my_my_engine/Engine.rb|270811|270812|270813|解释|270814|--full选项的用例似乎非常有限。就我个人而言，我想不出任何好的理由，为什么你想要将代码分离到一个引擎中，而不是隔离名称空间-它本质上只会给你提供两个紧密耦合的应用程序，共享相同的文件结构，以及由此带来的所有冲突和代码泄漏。|270815|我看到的每一篇文档都演示了--mountable选项，实际上，当前的edge+guide强烈鼓励您包含isolate+namespace-这等同于说使用--mountable而不是--full。|270816|最后是术语混淆:不幸的是，rails+plugin+-h显示了以下描述：|270817|270818|+--full+#使用捆绑的Rails应用程序生成用于测试的rails引擎|270819|270820|--mountable+#生成可挂载的隔离应用程序|270821|270822|这给人的印象是，您使用--full创建“引擎”，使用--mountable创建其他称为“可挂载的应用程序”的东西，而实际上它们都是引擎-一个名称空间，一个没有。这必然会导致混淆，因为希望创建引擎的用户可能会认为--full是更相关的选项。|270823|结论|270824|270825|rails+plugin+new+something+--full+=您的应用程序名称空间中的引擎。(为什么you?)|unordered-list-item|270826|rails+plugin+new+something+--mountable+=+Engine会有自己的命名空间。(太棒了)|270827|270828|270829|参考文献|270830|270831|http://edgeguides.rubyonrails.org/engines.html|270832|http://api.rubyonrails.org/classes/Rails/Engine.html|270833|http://railscasts.com/episodes/277-mountable-engines|270834|https://github.com/rails/rails/pull/6499|270835|270836|entityMap|0|LINK|mutability|MUTABLE|url|1|http://edgeguides.rubyonrails.org/engines.html#inside-an-engine|2|3|4|5^0|N|B|1G|6|9|6|0|0|0|0|A|B|J|B|H|0|0|T|0|0|0|Y|0|0|0|5|6|G|N|7|6|G|0|0|4|0|0|0|5|0|0|0|Q|0|0|I|J|0|0|E|J|0|0|K|J|0|K|J|0|P|J|0|P|J|0|0|0|0|0|0|0|0|0|6|0|D|B|1F|H|24|B|2I|6|Y|A|1|0|D|F|0|0|U|7|0|0|0|0|B|6|Q|B|2X|6|0|0|0|0|X|0|0|12|0|0|0|0|0|0|1A|2|0|0|1G|3|0|0|1G|4|0|0|14|5|0|0^^$0|@$1|2|3|4|5|6|7|3E|8|@$9|3F|A|3G|B|C]|$9|3H|A|3I|B|C]]|D|@$9|3J|A|3K|1|3L]]|E|$]]|$1|F|3|G|5|6|7|3M|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|3N|8|@$9|3O|A|3P|B|J]|$9|3Q|A|3R|B|J]|$9|3S|A|3T|B|C]]|D|@]|E|$]]|$1|K|3|L|5|6|7|3U|8|@$9|3V|A|3W|B|J]]|D|@]|E|$]]|$1|M|3|N|5|O|7|3X|8|@]|D|@]|E|$P|Q]]|$1|R|3|S|5|6|7|3Y|8|@$9|3Z|A|40|B|J]]|D|@]|E|$]]|$1|T|3|U|5|O|7|41|8|@]|D|@]|E|$P|Q]]|$1|V|3|W|5|6|7|42|8|@$9|43|A|44|B|J]|$9|45|A|46|B|J]|$9|47|A|48|B|J]|$9|49|A|4A|B|C]]|D|@]|E|$]]|$1|X|3|Y|5|6|7|4B|8|@$9|4C|A|4D|B|J]]|D|@]|E|$]]|$1|Z|3|10|5|O|7|4E|8|@]|D|@]|E|$P|Q]]|$1|11|3|12|5|6|7|4F|8|@$9|4G|A|4H|B|J]]|D|@]|E|$]]|$1|13|3|14|5|O|7|4I|8|@]|D|@]|E|$P|Q]]|$1|15|3|16|5|6|7|4J|8|@$9|4K|A|4L|B|J]]|D|@]|E|$]]|$1|17|3|-4|5|6|7|4M|8|@]|D|@]|E|$]]|$1|18|3|19|5|1A|7|4N|8|@$9|4O|A|4P|B|J]]|D|@]|E|$]]|$1|1B|3|-4|5|6|7|4Q|8|@]|D|@]|E|$]]|$1|1C|3|1D|5|6|7|4R|8|@$9|4S|A|4T|B|J]]|D|@]|E|$]]|$1|1E|3|1F|5|6|7|4U|8|@]|D|@]|E|$]]|$1|1G|3|1H|5|6|7|4V|8|@$9|4W|A|4X|B|J]]|D|@]|E|$]]|$1|1I|3|1J|5|6|7|4Y|8|@$9|4Z|A|50|B|J]]|D|@]|E|$]]|$1|1K|3|1L|5|6|7|51|8|@$9|52|A|53|B|J]]|D|@]|E|$]]|$1|1M|3|1N|5|6|7|54|8|@$9|55|A|56|B|J]]|D|@]|E|$]]|$1|1O|3|1P|5|6|7|57|8|@]|D|@]|E|$]]|$1|1Q|3|1R|5|6|7|58|8|@]|D|@]|E|$]]|$1|1S|3|1T|5|6|7|59|8|@]|D|@]|E|$]]|$1|1U|3|1V|5|6|7|5A|8|@]|D|@]|E|$]]|$1|1W|3|-4|5|6|7|5B|8|@]|D|@]|E|$]]|$1|1X|3|-4|5|6|7|5C|8|@]|D|@]|E|$]]|$1|1Y|3|1Z|5|6|7|5D|8|@]|D|@]|E|$]]|$1|20|3|21|5|6|7|5E|8|@$9|5F|A|5G|B|C]]|D|@]|E|$]]|$1|22|3|23|5|6|7|5H|8|@$9|5I|A|5J|B|C]|$9|5K|A|5L|B|C]|$9|5M|A|5N|B|C]|$9|5O|A|5P|B|C]]|D|@$9|5Q|A|5R|1|5S]]|E|$]]|$1|24|3|25|5|6|7|5T|8|@$9|5U|A|5V|B|C]]|D|@]|E|$]]|$1|26|3|-4|5|6|7|5W|8|@]|D|@]|E|$]]|$1|27|3|28|5|1A|7|5X|8|@$9|5Y|A|5Z|B|J]]|D|@]|E|$]]|$1|29|3|-4|5|6|7|60|8|@]|D|@]|E|$]]|$1|2A|3|2B|5|6|7|61|8|@]|D|@]|E|$]]|$1|2C|3|-4|5|6|7|62|8|@]|D|@]|E|$]]|$1|2D|3|2E|5|6|7|63|8|@$9|64|A|65|B|C]|$9|66|A|67|B|C]|$9|68|A|69|B|C]]|D|@]|E|$]]|$1|2F|3|2G|5|6|7|6A|8|@]|D|@]|E|$]]|$1|2H|3|-4|5|6|7|6B|8|@]|D|@]|E|$]]|$1|2I|3|2J|5|2K|7|6C|8|@$9|6D|A|6E|B|C]]|D|@]|E|$]]|$1|2L|3|2M|5|2K|7|6F|8|@$9|6G|A|6H|B|C]]|D|@]|E|$]]|$1|2N|3|-4|5|6|7|6I|8|@]|D|@]|E|$]]|$1|2O|3|-4|5|6|7|6J|8|@]|D|@]|E|$]]|$1|2P|3|2Q|5|6|7|6K|8|@]|D|@]|E|$]]|$1|2R|3|-4|5|6|7|6L|8|@]|D|@]|E|$]]|$1|2S|3|2T|5|2K|7|6M|8|@]|D|@$9|6N|A|6O|1|6P]]|E|$]]|$1|2U|3|2V|5|2K|7|6Q|8|@]|D|@$9|6R|A|6S|1|6T]]|E|$]]|$1|2W|3|2X|5|2K|7|6U|8|@]|D|@$9|6V|A|6W|1|6X]]|E|$]]|$1|2Y|3|2Z|5|2K|7|6Y|8|@]|D|@$9|6Z|A|70|1|71]]|E|$]]|$1|30|3|-4|5|6|7|72|8|@]|D|@]|E|$]]|$1|31|3|-4|5|6|7|73|8|@]|D|@]|E|$]]]|32|$33|$5|34|35|36|E|$37|2V]]|38|$5|34|35|36|E|$37|39]]|3A|$5|34|35|36|E|$37|2T]]|3B|$5|34|35|36|E|$37|2V]]|3C|$5|34|35|36|E|$37|2X]]|3D|$5|34|35|36|E|$37|2Z]]]]

Both options will generate an <a href="http://api.rubyonrails.org/classes/Rails/Engine.html" rel="noreferrer">engine</a>. The difference is that <code>--mountable</code> will create the engine in an isolated namespace, whereas <code>--full</code> will create an engine that shares the namespace of the main app.
The differences will be manifested in 3 ways:
1) The engine class file will call <code>isolate_namespace</code>:
lib/my_full_engine/engine.rb:
<pre><code>module MyFullEngine
 class Engine &lt; Rails::Engine
 end
end
</code></pre>
lib/my_mountable_engine/engine.rb:
<pre><code>module MyMountableEngine
 class Engine &lt; Rails::Engine
 isolate_namespace MyMountableEngine # --mountable option inserted this line
 end
end
</code></pre>
2) The engine's <code>config/routes.rb</code> file will be namespaced:
Full engine:
<pre><code>Rails.application.routes.draw do
end
</code></pre>
Mounted engine:
<pre><code>MyMountableEngine::Engine.routes.draw do
end
</code></pre>
3) The file structure for controllers, helpers, views, and assets will be namespaced:
<blockquote>
create app/controllers/my_mountable_engine/application_controller.rb 
create app/helpers/my_mountable_engine/application_helper.rb 
create app/mailers create app/models 
create app/views/layouts/my_mountable_engine/application.html.erb 
create app/assets/images/my_mountable_engine 
create app/assets/stylesheets/my_mountable_engine/application.css 
create app/assets/javascripts/my_mountable_engine/application.js 
create config/routes.rb create lib/my_mountable_engine.rb 
create lib/tasks/my_mountable_engine.rake 
create lib/my_mountable_engine/version.rb 
create lib/my_mountable_engine/engine.rb
</blockquote>
<hr />
<h2>Explanation</h2>
The use case for the <code>--full</code> option seems to be very limited. Personally I can't think of any good reason why you'd want to separate your code into an engine without isolating the namespace as well- It would essentially just give you two tightly coupled applications sharing identical file structures and all the conflicts and code leakage that entails.
Every piece of documentation I've seen demonstrates the <code>--mountable</code> option, and indeed the current <a href="http://edgeguides.rubyonrails.org/engines.html#inside-an-engine" rel="noreferrer">edge guide</a> strongly encourages you to include <code>isolate namespace</code>- which is the same as saying use <code>--mountable</code> over <code>--full</code>.
Finally there's terminology confusion: Unfortunately <code>rails plugin -h</code> shows the following descriptions:
<blockquote>
[--full] # Generate a rails engine with bundled Rails application for testing 
[--mountable] # Generate mountable isolated application
</blockquote>
This gives the impression that you use <code>--full</code> to create an &quot;engine&quot; and <code>--mountable</code> to create something else called a &quot;mountable application&quot;, when in fact they're both engines - one namespaced and one not. That's bound to lead to confusion as users looking to create an engine will likely assume that <code>--full</code> is the more relevant option.
<h2>Conclusion</h2>
<ul>
<li><code>rails plugin new something --full</code> = Engine in your app's namespace. (Why would you?)</li>
<li><code>rails plugin new something --mountable</code> = Engine with it's own namespace. (Awesome)</li>
</ul>
<hr />
<h2>References</h2>
<ul>
<li><a href="http://edgeguides.rubyonrails.org/engines.html" rel="noreferrer">http://edgeguides.rubyonrails.org/engines.html</a></li>
<li><a href="http://api.rubyonrails.org/classes/Rails/Engine.html" rel="noreferrer">http://api.rubyonrails.org/classes/Rails/Engine.html</a></li>
<li><a href="http://railscasts.com/episodes/277-mountable-engines" rel="noreferrer">http://railscasts.com/episodes/277-mountable-engines</a></li>
<li><a href="https://github.com/rails/rails/pull/6499" rel="noreferrer">https://github.com/rails/rails/pull/6499</a></li>
</ul>

Can someone help me understand the differences between a Rails Engine and a Mountable app? In Rails 3.1, you can create either one with the "rails new plugin ___" command.

<pre><code>rails plugin new forum --full # Engine
rails plugin new forum --mountable # Mountable App
</code></pre>

When would you want to use one versus the other? I know you can package an Engine as a gem, for one. Is that not the case for Mountable Apps? What other differences are there?

Rails 3.1: Engine vs. Mountable App

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有人能帮我理解一下Rails引擎和可安装的应用程序之间的区别吗？在Rails3.1中，您可以使用"rails new plugin ___“”命令创建任何一个插件。rails plugin new forum --full        # Enginerails plugin new forum --mountabl...

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