|=” operator in Rails ? What is its significance? [duplicate]

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Possible Duplicate: What does the operator

||=最先在C语言中流行起来的二进制运算符速记，例如：。

就像:

为了更有效的短路而进行的重排是一种处理nil检查的优雅方式，因为如果可以的话，它完全避免了赋值。赋值可能有副作用。|= is called the T-square operator I believe.

@_current_user ||= session[:current_user_id] &&
      User.find(session[:current_user_id])

or

Answer 1

Look at the blog below for more info on the "T-square" operator:

@_current_user ||= {SOMETHING}

http:@_current_user请看 {SOMETHING}http:/www.rubyinside.comwhat-rubys-double-pipe-or-equals-really-does-5488.htmlnil 以获得更详细的解释。false @_current_user

@_current_user || @_current_user = {SOMETHING}

如果你有C#的经验，我相信它类似于C#中的null-coalescing (?)操作符（但更多的是Ruby技巧）。

session[:current_user_id] &&
      User.find(session[:current_user_id])

如果x不为空，则x被分配给y，否则使用 "默认 "值-1。&&同样，/blogs.oracle.comprashantentrythe_ruby_t_square_operator也是如此。session[:current_user_id] User.find(session[:current_user_id]) User.find(session[:current_user_id])