防止副作用红宝石

Question

a = [1,2,3,4] 
b = a << 5 
a == [1,2,3,4] # returns false 

如何分配b到a与5追加到末尾，而无需修改a本身？

Answer 1

红宝石变量持有引用对象和=操作复制引用。

看来你想clonea：

irb(main):001:0> a = [1,2,3,4] 
=> [1, 2, 3, 4] 
irb(main):002:0> b = a.clone << 5 
=> [1, 2, 3, 4, 5] 
irb(main):003:0> a 
=> [1, 2, 3, 4] 
irb(main):004:0> b 
=> [1, 2, 3, 4, 5] 

Answer 2

算了笔两个数组：

a = [1,2,3,4] 
b = a + [5] 

# b == [1, 2, 3, 4, 5] 
# a == [1, 2, 3, 4] 

Answer 3

我通常做这种方式：

b = [*a, 5]