如何访问“全球” （常数？）类的capistrano变量？ （红宝石） [英] How to access "global" (constant?) capistrano variables from classes? (ruby)

问题描述

 要求'capistrano / capistrano'开始像这样，我猜这是非常正常的： ext / multistage'
 require'nokogiri'
 require'curb'
 require'json'
 
＃覆盖capistrano默认值
 set：use_sudo，false 
 set：normalize_asset_timestamps，false 
 
＃我的一些常数
 set：my_constant，foo_bar
  

稍后，我可以在名称空间中的函数或任务中访问常量，如：

  namespace：mycompany do 
 def some_function（）
运行some_command＃{my_constant}
结束
 
 desc <<< -DESC 
一些任务描述
 DESC 
任务：some_task do 
运行some_command＃{my_constant}
结束
结束
  

但是，如果我在类中使用常量，如下所示：

  namespace：mycompany do 
 class SomeClass 
 def self.some_static_method（）
运行some_command＃{my_constant}
结束$ b $结束
结束
  

失败：

  / config / deploy。 rb：120：在some_static_method中：未定义的局部变量或方法my_constant为＃< Class：0x000000026234f8> :: SomeClass（NameError）
  

我做错了什么？
谢谢

解决方案

deploy.rb文件是instance_evaled，这意味着它在对象的上下文中执行，因此您声明的任何内容都将在您离开该情境之前可用。创建一个提供新上下文的类。

为了访问原始上下文，您必须将对象（self）传递给类方法。 / b>

  namespace：mycompany do 
类SomeClass 
 def self.some_static_method（cap）
 run some_command＃{cap.fetch（：my_constant）}
 end 
 end 
 
 SomeClass.some_static_method（self）
 end 
  

虽然我真的不明白为什么要声明这样的类，但这是一个奇怪的地方。

So my deploy.rb script in capistrano starts like this, which I guess is pretty normal:

require 'capistrano/ext/multistage'
require 'nokogiri'
require 'curb'
require 'json'

# override capistrano defaults
set :use_sudo, false
set :normalize_asset_timestamps, false

# some constant of mine
set :my_constant, "foo_bar"

Later, I can access my constant in functions or tasks within namespaces, like:

namespace :mycompany do
    def some_function()
        run "some_command #{my_constant}"
    end

    desc <<-DESC
        some task description
    DESC
    task :some_task do
        run "some_command #{my_constant}"
    end
end

However, if I use the constant in a class, like this:

namespace :mycompany do
    class SomeClass
        def self.some_static_method()
            run "some_command #{my_constant}"
        end
    end
end

It fails with:

/config/deploy.rb:120:in `some_static_method': undefined local variable or method `my_constant' for #<Class:0x000000026234f8>::SomeClass (NameError)

What am I doing wrong?? Thanks

解决方案

The deploy.rb file is instance_evaled, this means it's being executed inside the context of an object, and as such anything you declare will be available until you leave that context. As soon as you create a class that provides a new context.

In order to access the original context you have to pass the object (self) to the class method.

namespace :mycompany do
  class SomeClass
    def self.some_static_method(cap)
      run "some_command #{cap.fetch(:my_constant)}"
    end
  end

  SomeClass.some_static_method(self)
end

Although I really don't understand why you are declaring a class like this, it's an odd place for it.

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