安全导航运算符 (&.) 的语法糖

Question

str = "Hello World!"
str.[] /Hello/    # => "Hello"
str[/Hello/]      # => "Hello", syntactic suger version

str = nil
str&.[] /Hello/   # => nil
str&.[/Hello/]    # => SyntaxError: unexpected '[', expecting '('
str[/Hello/]      # => NoMethodError: undefined method `[]' for nil:NilClass

如何在 [] 方法的语法糖上使用安全导航运算符 (&.)？

Answer 1

How can the Safe Navigation operator(&.) be used on syntactic sugar for []method?

不能。 Matz 不想这样。

此功能已被请求并被拒绝两次：

• Bug #11618: Safe call syntax with aref or aset is
• Feature #11813: Extend safe navigation operator for [] and []= with syntax sugar

Matz says:

I am not going to add safe navigation for aref and aset. Maybe you can use a.?[](x) (method call of an operator).

Answer 2

答案很简短 - 你不能。因为 "method name is syntactically required" 来自 Ruby 2.3 新闻