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最新推荐文章于 2025-12-02 16:58:01 发布

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本文介绍了一种在Ruby中处理变量参数列表及命名参数的方法。通过定义add和subtract方法实现数值加减运算，并进一步扩展到calculate方法，该方法可根据传入的选项参数决定执行加法或减法操作。

First I should say rubymonk is a great web site for ruby learners.

I just have some time this afternoon so I dived my self into this language and found it quite amazing!

Look at this code snippet below. Besides a variable parameter list, it's also possible to add naming parameters to your method arguments.


def add(*numbers)
	numbers.inject(0) { |sum, number| sum + number }  
end

def subtract(*numbers)
  sum = numbers.shift
  numbers.inject(sum) { |sum, number| sum - number }  
end

def calculate(*arguments)
  # if the last argument is a Hash, extract it 
  # otherwise create an empty Hash
  options = arguments[-1].is_a?(Hash) ? arguments.pop : {}
  options[:add] = true if options.empty?
  return add(*arguments) if options[:add]
  return subtract(*arguments) if options[:subtract]
end


invoking add(4, 5) returns 9 ✔
invoking add(-10, 2, 3) returns -5 ✔
invoking add(0, 0, 0, 0) returns 0 ✔
invoking subtract(4, 5) returns -1 ✔
invoking subtract(-10, 2, 3) returns -15 ✔
invoking subtract(0, 0, 0, 0, -10) returns 10 ✔
defaults to addtion when no option is specified ✔
invoking calculate(4, 5, add: true) returns 9 ✔
invoking calculate(-10, 2, 3, add: true) returns -5 ✔
invoking calculate(0, 0, 0, 0, add: true) returns 0 ✔
invoking calculate(4, 5, subtract: true) returns -1 ✔
invoking calculate(-10, 2, 3, subtract: true) returns -15 ✔
invoking calculate(0, 0, 0, 0, -10, subtract: true) returns 10 ✔