（另一個）堆棧級別太深紅寶石

Question

我在調用本身的一個方法（遞歸循環），我會很感激一些單詞，方法或更正的代碼來解決這個問題。

代碼：

class Person_verifier 
    def initialize(first_name, ssn) 
    @first_name = first_name 
    @ssn = ssn.to_s 
    end 
    def first_name 
    @first_name 
    end 
    def ssn 
    if ssn[9] =~ /[1, 3, 5, 7, 9]/ 
     "#{first_name}'s social security number is #{ssn} and based on the second-last number, #{first_name} is a Male" 
    elsif ssn[9] =~ /[0, 2, 4, 6, 8]/ 
     "#{first_name}'s social security number is #{ssn} and based on the second-last number, #{first_name} is a Female" 
    else 
     return false 
    end 
    end 
end 

IRB輸出：

load './ssn.rb' 
d = Person_verifier.new("MyName", "010285-123X") 
d.first_name 
# => "MyName" 
d.ssn 
# => SystemStackError: stack level too deep 
    from /home/username/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/irb/workspace.rb:86 
    Maybe IRB bug! 

Answer 1

def ssn 
    if @ssn[9] =~ /[1, 3, 5, 7, 9]/ 
    "#{first_name}'s social security number is #{@ssn} and based on the second-last number, #{first_name} is a Male" 
    elsif @ssn[9] =~ /[0, 2, 4, 6, 8]/ 
    "#{first_name}'s social security number is #{@ssn} and based on the second-last number, #{first_name} is a Female" 
    else 
    return false 
    end 
end 

上面的代碼應該工作。您只需在方法內部使用@符號作爲ssn。否則，很顯然，遞歸調用正在發生，當您嘗試對您的ssn進行字符串插值時。請注意，該實例變量僅在@中可見。這不是隱含的。顯然，你會遇到類似於你遇到的問題。