结合Ruby中的许多if条件

Question

只是想知道，还有更好的方法来写这个：

if key != "a" && key != "b" && key != "c"
  ...
end

或许连接上述条件？

Answer 1

unless ["a", "b", "c"].include?(key)
    # ...
end

Answer 2

case key
when "a", "b", "c"
else
  ...
end

Answer 3

unless %w(a b c).include?(key)
  # ...
end

Answer 4

尝试Array#include：

if not ["a", "b", "c"].include? key
  ...

更简洁一点。

Answer 5

一种方法是使用include：

if !%w(a b c).include?(key) then
  ...
end

Answer 6

if %w( a b c ).exclude?(key)
  ...
end

来自active_support

Answer 7

unless key[/[abc]/]
  ...
end

...但我更喜欢sawa的答案以便于阅读。