[英]What does the “$” character mean in Ruby?
Been playing with Ruby on Rails for awhile and decided to take a look through the actual source. 一直在使用Ruby on Rails并决定查看实际来源。 Grabbed the repo from GitHub and started looking around.
抓住GitHub的回购并开始环顾四周。 Came across some code that I am not sure what it does or what it references.
遇到一些代码,我不知道它做了什么或它引用了什么。
I saw this code in actionmailer/test/abstract_unit.rb 我在actionmailer / test / abstract_unit.rb中看到了这段代码
root = File.expand_path('../../..', __FILE__)
begin
require "#{root}/vendor/gems/environment"
rescue LoadError
$:.unshift("#{root}/activesupport/lib")
$:.unshift("#{root}/actionpack/lib")
end
lib = File.expand_path("#{File.dirname(__FILE__)}/../lib")
$:.unshift(lib) unless $:.include?('lib') || $:.include?(lib)
require 'rubygems'
require 'test/unit'
require 'action_mailer'
require 'action_mailer/test_case'
Can someone tell me what the $: (aka "the bling") is referencing? 有人能告诉我$ :(又名“bling”)引用了什么?
$
identifies a global variable, as opposed to a local variable, @instance variable, or @@class variable. $
标识全局变量,而不是局部变量,@ instance变量或@@类变量。
Among the language-supplied global variables are $:
, which is also identified by $LOAD_PATH
语言提供的全局变量中有
$:
,它也由$LOAD_PATH
标识
$: is the global variable used for looking up external files. $:是用于查找外部文件的全局变量。
From http://www.zenspider.com/Languages/Ruby/QuickRef.html#18 来自http://www.zenspider.com/Languages/Ruby/QuickRef.html#18
$: Load path for scripts and binary modules by load or require.
$:按加载或要求加载脚本和二进制模块的路径。
To quote the Ruby Forum: 引用Ruby论坛:
ruby comes with a set of predefined variables ruby带有一组预定义变量
$: = default search path (array of paths)
__FILE__ = current sourcefile
if i get it right (not 100% sure) this adds the lib path to this array of search paths by going over the current file. 如果我做对了(不是100%肯定),这将通过遍历当前文件将lib路径添加到此搜索路径数组。 which is not exactly the best way, i would simply start with RAILS_ROOT (at least for a rails project)
这不是最好的方式,我只想从RAILS_ROOT开始(至少对于一个rails项目)
I wanna note something weird about Ruby! 我想注意一些关于Ruby的奇怪之处!
$
does indeed mean load path. $
确实意味着加载路径。 And ;
而且
;
means "end line". 意思是“终点线”。 But!
但!
$;
means field separator. 表示字段分隔符。 Try running
$;.to_s
in your REPL and you'll see it return ","
. 尝试在REPL中运行
$;.to_s
,你会看到它返回","
。 That's not all! 那不是全部!
$
with other suffixes can mean many other things . $
与其他后缀可能意味着许多其他事情 。
Why? 为什么? Well, Perl of course!
好吧,Perl当然!
$:.unshift
is the same as 是相同的
$LOAD_PATH.unshift
. 。 You can also say:
你也可以说:
$: <<
$LOAD_PATH <<
They are pretty common Ruby idioms to set a load path. 它们是设置加载路径的常用Ruby习语。
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