ruby - 使用可枚举获取所有项目#take

Question

我怎样才能 Enumerable#take 所有的东西？

arr = [1, 2, 3]
# Works
arr.take(1)
# Gives RangeError: float Inf out of range of integer
arr.take(Float::INFINITY)
# Gives RangeError: float Inf out of range of integer
arr.take(1.0/0.0)
# RangeError: bignum too big to convert into `long'
arr.take(1000_000_000_000_000_000_000_000_000_000_000_000_000_000_000_000_000)
# TypeError: no implicit conversion from nil to integer
arr.take(nil)

如果无法使用 Enumerable#take 获取所有项目，那么我必须在 display_results_allowing_all_objects 中使用复杂的代码，而不是在 display_results 中使用简单的代码。

MAX_ROWS = 1

# Simple code: Only two lines long.    
def display_results(results)
  results_to_display = results.take(MAX_ROWS)
  puts results_to_display.map{|result| result.join("\t")}.join("\n")
end

results = [["Foo", 1], ["Bar", 2], ["Baz", 3]]

display_results(results)

NEW_MAX_ROWS = Float::INFINITY

# Convoluted mess: six lines long
def display_results_allowing_all_objects(results)
  results_to_display = if NEW_MAX_ROWS == Float::INFINITY
                         results
                       else
                         results_to_display = results.take(NEW_MAX_ROWS)
                       end
  puts results_to_display.map{|result| result.join("\t")}.join("\n")
end

display_results_allowing_all_objects(results)

Answer 1

您可以使用 Enumerable#take_while拿走所有元素

$> arr.take_while { true }
 # => [1, 2, 3]