在Ruby中ENV返回什么对象？

有一个我们都知道的环境变量。它返回一个对象。但是ENV的返回值在视觉上类似于散列。但事实并非如此

例如：

> ENV
=> {"SHELL"=>"/bin/bash", "SESSION_MANAGER"=>"local/archlinux:@/tmp/.ICE-unix/613,unix/archlinux:/tmp/.ICE-unix/613", "COLORTERM"=>"truecolor", "XDG_CONFIG_DIRS"=>"/etc/xdg", "XDG_MENU_PREFIX"=>"xfce-", "SSH_AUTH_SOCK"=>"/tmp/ssh-Al0pdO1R5970/agent.622", "DESKTOP_SESSION"=>"Xfce Session", "SSH_AGENT_PID"=>"623", "GTK_MODULES"=>"canberra-gtk-module:canberra-gtk-module", "XDG_SEAT"=>"seat0", "PWD"=>"/home/sourav", "LOGNAME"=>"sourav", "XDG_SESSION_TYPE"=>"x11", "XAUTHORITY"=>"/home/sourav/.Xauthority", "HOME"=>"/home/sourav", "LANG"=>"en_GB.UTF-8", "XDG_CURRENT_DESKTOP"=>"XFCE", "VTE_VERSION"=>"5603", "INVOCATION_ID"=>"6d4dc7a91cc141e691436cb850e18f8d", "GLADE_CATALOG_PATH"=>":", "XDG_SESSION_CLASS"=>"user", "TERM"=>"xterm-256color", "USER"=>"sourav", "DISPLAY"=>":0.0", "SHLVL"=>"2", "XDG_VTNR"=>"1", "XDG_SESSION_ID"=>"1", "TILIX_ID"=>"f2480263-263e-408f-be36-8105e71256a6", "MOZ_PLUGIN_PATH"=>"/usr/lib/mozilla/plugins", "GLADE_MODULE_PATH"=>":", "XDG_RUNTIME_DIR"=>"/run/user/1000", "GLADE_PIXMAP_PATH"=>":", "JOURNAL_STREAM"=>"9:25041", "XDG_DATA_DIRS"=>"/usr/local/share:/usr/share", "PATH"=>"/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/sourav/.rvm/bin:/home/sourav/.rvm/bin:/home/sourav/.gem/ruby/2.6.0/bin", "DBUS_SESSION_BUS_ADDRESS"=>"unix:path=/run/user/1000/bus", "MAIL"=>"/var/spool/mail/sourav", "_"=>"/home/sourav/.irb", "LINES"=>"24", "COLUMNS"=>"80"}

看起来类似于：

> ENV.to_h
=> {"SHELL"=>"/bin/bash", "SESSION_MANAGER"=>"local/archlinux:@/tmp/.ICE-unix/613,unix/archlinux:/tmp/.ICE-unix/613", "COLORTERM"=>"truecolor", "XDG_CONFIG_DIRS"=>"/etc/xdg", "XDG_MENU_PREFIX"=>"xfce-", "SSH_AUTH_SOCK"=>"/tmp/ssh-Al0pdO1R5970/agent.622", "DESKTOP_SESSION"=>"Xfce Session", "SSH_AGENT_PID"=>"623", "GTK_MODULES"=>"canberra-gtk-module:canberra-gtk-module", "XDG_SEAT"=>"seat0", "PWD"=>"/home/sourav", "LOGNAME"=>"sourav", "XDG_SESSION_TYPE"=>"x11", "XAUTHORITY"=>"/home/sourav/.Xauthority", "HOME"=>"/home/sourav", "LANG"=>"en_GB.UTF-8", "XDG_CURRENT_DESKTOP"=>"XFCE", "VTE_VERSION"=>"5603", "INVOCATION_ID"=>"6d4dc7a91cc141e691436cb850e18f8d", "GLADE_CATALOG_PATH"=>":", "XDG_SESSION_CLASS"=>"user", "TERM"=>"xterm-256color", "USER"=>"sourav", "DISPLAY"=>":0.0", "SHLVL"=>"2", "XDG_VTNR"=>"1", "XDG_SESSION_ID"=>"1", "TILIX_ID"=>"f2480263-263e-408f-be36-8105e71256a6", "MOZ_PLUGIN_PATH"=>"/usr/lib/mozilla/plugins", "GLADE_MODULE_PATH"=>":", "XDG_RUNTIME_DIR"=>"/run/user/1000", "GLADE_PIXMAP_PATH"=>":", "JOURNAL_STREAM"=>"9:25041", "XDG_DATA_DIRS"=>"/usr/local/share:/usr/share", "PATH"=>"/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl:/home/sourav/.rvm/bin:/home/sourav/.rvm/bin:/home/sourav/.gem/ruby/2.6.0/bin", "DBUS_SESSION_BUS_ADDRESS"=>"unix:path=/run/user/1000/bus", "MAIL"=>"/var/spool/mail/sourav", "_"=>"/home/sourav/.irb", "LINES"=>"24", "COLUMNS"=>"80"}

但是：

---

那么ENV返回什么类型的对象呢？

它是一个自定义对象，具有散列函数，主要用C实现

---

Ruby语言规范中没有要求以任何特定方式实现

ENV

。只要它以正确的方式响应正确的消息，它就可以是它想要的任何东西

例如，在Rubinius中，

ENV

是在一个名为

Rubinius:：EnvironmentVariables

的类中实现的，该类实现了

散列协议的一部分，还混合了
可枚举的
：

> ENV.to_h.eql?(ENV)
=> false