執行方法調用

Question

我正在玩弄創建DSL。我使用http://jroller.com/rolsen/entry/building_a_dsl_in_ruby作爲指導。

鑑於這種DSL：

question 'Who was the first president of the USA?' 
wrong 'Fred Flintstone' 
wrong 'Martha Washington' 
right 'George Washington' 
wrong 'George Jetson' 

是有辦法，以確保問題（）被調用至少一次，右（）一次，以及錯誤的（）N次或更多次？

Answer 1

當然。只需添加一行

(@question_count ||= 0) += 1 

到無論你目前執行的question方法的樣子（以及類似的right和wrong），然後檢查這些變量。

Answer 2

應答的處理缺少在下面的代碼，但是你只有一個正確答案的控制

class Question 
    def initialize(text) 
    @text = text 
    @answers = [] 
    @correct = nil #index of the correct answer inside @answers 
    end 
    def self.define(text, &block) 
    raise ArgumentError, "Block missing" unless block_given? 
    q = self.new(text) 
    q.instance_eval(&block)  
    q 
    end 
    def wrong(answer) 
    @answers << answer 
    end 
    def right(answer) 
    raise "Two right answers" if @correct 
    @answers << answer 
    @correct = @answers.size 
    end 
    def ask() 
    puts @text 
    @answers.each_with_index{|answer, i| 
     puts "\t%2i %s?" % [i+1,answer] 
    } 
    puts "correct is %i" % @correct 
    end 
end 

def question(text, &block) 
    raise ArgumentError, "Block missing" unless block_given? 
    Question.define(text, &block) 
end 

現在你可以用塊語法定義你的問題：

question('Who was the first president of the USA?') { 
    wrong 'Fred Flintstone' 
    wrong 'Martha Washington' 
    right 'George Washington' 
    wrong 'George Jetson' 
}.ask 

您可能也使用另一個定義的問題：

q = Question.new('Who was the first president of the USA?') 
q.wrong 'Fred Flintstone' 
q.wrong 'Martha Washington' 
q.right 'George Washington' 
q.wrong 'George Jetson' 
q.ask