带块的可选参数？

Question

# multi_map
# Write a method multi_map that accepts an array, an optional number (n), and a block as arguments. 
# The method should return a new array where each element of the original array is repeatedly run through the block n times. 
# If the number argument is not passed in, then the the elements should be run through the block once.

# Examples
def multi_map(arr, &blc, *n)
    narr = [] 

   
    return narr
end

p multi_map(['pretty', 'cool', 'huh?']) { |s| s + '!'}      # ["pretty!", "cool!", "huh?!"]
p multi_map(['pretty', 'cool', 'huh?'], 1) { |s| s + '!'}   # ["pretty!", "cool!", "huh?!"]
p multi_map(['pretty', 'cool', 'huh?'], 3) { |s| s + '!'}   # ["pretty!!!", "cool!!!", "huh?!!!"]
p multi_map([4, 3, 2, 7], 1) { |num| num * 10 }             # [40, 30, 20, 70]
p multi_map([4, 3, 2, 7], 2) { |num| num * 10 }             # [400, 300, 200, 700]
p multi_map([4, 3, 2, 7], 4) { |num| num * 10 }             # [40000, 30000, 20000, 70000]

我需要制作一个接受数组、可选和块的方法。当我在 rspec 中运行这个框架程序时，我在调用参数时遇到错误。为什么会这样？

Answer 1

考虑以下几点：

irb(main):010:1* def mm(arr, *n, &blc)
irb(main):011:1*   p arr; n.each(&blc)
irb(main):012:0> end
=> :mm
irb(main):013:0> mm("hello", "world") { |x| puts x }
"hello"
world
=> ["world"]
irb(main):014:0>

您在参数列表中的 *n 和 &blc 顺序错误。

带块的可选参数？

Optional Parameters with blocks?

ruby

arrays

reference

block

optional-arguments