在Array類中禁用隨機播放和樣本

假設我們希望有人編寫自己的僞隨機方法。作爲編程練習。我們希望每次他們試圖解決內置了功能快捷在Array類中禁用隨機播放和樣本

到目前爲止的時間產生一個錯誤，這是我做了什麼：

ERROR_STRING_FOR_RANDOM = "Usage of built-in random generators is not allowed" 

methods_to_block = ["rand", "srand", "Random::rand", "Random::srand", 
"Random::seed", "Random::new", "Kernel::rand", "Kernel::srand", 
"Array::shuffle", "Array::shuffle!", "Array::sample"] 

methods_to_block.each do |method| 
    eval 
    """ 
    def #{method} 
    raise ERROR_STRING_FOR_RANDOM 
    end 
    """ 
end

所以，它阻止隨機的，這些加薪一個錯誤：

rand 
srand 
Random.new.rand(18)

但它不適用於數組的僞隨機方法。例如

[1,2,3].shuffle!

仍然有效。爲什麼會發生這種情況，以及如何預防它？

來源

2016-04-07 Jade Turing

您可以打開類和替換要禁用的方法...

class Array 
    ERROR_STRING_FOR_RANDOM = "Usage of built-in random generators is not allowed" 
    RANDOM_METHODS = [:shuffle, :shuffle!, :select] 
    def rajarshi_random_error 
    raise ERROR_STRING_FOR_RANDOM 
    end 
    RANDOM_METHODS.each do |m| 
    define_method(m) {|*args| rajarshi_random_error } 
    end 
end

來源

2016-04-07 14:35:48 SteveTurczyn

:)）.............. ......... –

你的代碼是越來越錯誤

ArgumentError: wrong number of arguments (0 for 1..4)

但對於其他類似的模塊功能，你可以這樣定義

methods_to_block = ["rand", "srand","seed", "sample", "shuffle!", "shuffle!"]

方法應該看起來像

methods_to_block.each do |method| 
    define_method "#{method}" do 
    raise ERROR_STRING_FOR_RANDOM 
    end 
end 
#=> ["rand", "srand", "Random::rand", "Random::srand", "Random::seed", "Random::new", "Kernel::rand", "Kernel::srand", "Array::shuffle", "Array::shuffle!", "Array::sample"]

現在，如果您致電

> srand 
RuntimeError: Usage of built-in random generators is not allowed 

> rand 
RuntimeError: Usage of built-in random generators is not allowed

希望它會幫助你

如果你想堅持保持自己的方式

ERROR_STRING_FOR_RANDOM = "Usage of built-in random generators is not allowed" 

methods_to_block = ["rand", "srand", "Random::rand", "Random::srand", 
"Random::seed", "Random::new", "Kernel::rand", "Kernel::srand", 
"Array::shuffle", "Array::shuffle!", "Array::sample"] 


methods_to_block.each do |method| 
if method.split("::").size > 1 && method.split("::").first != "Kernel" 
class_name = method.split("::").first 
method_name = method.split("::").last 
er = <<ER 
class #{class_name} 
def #{method_name} 
raise ERROR_STRING_FOR_RANDOM 
end 
end 
ER 
eval(er) 
else 
define_method "#{method}" do 
raise ERROR_STRING_FOR_RANDOM 
end 
end 
end

現在你可以得到所有

> srand 
RuntimeError: Usage of built-in random generators is not allowed 

> rand 
RuntimeError: Usage of built-in random generators is not allowed 

> [2,3,4,5].shuffle 
RuntimeError: Usage of built-in random generators is not allowed

來源

2016-04-07 14:16:49

好的。這工作：

class Array 
    undef_method :sample, :shuffle, :shuffle! 
end

使用範圍解析運算符是錯誤的想法開始。他們只是創建內部類的常量，而不是重新定義方法

同樣，適當的方法來禁用蘭特和函數srand看起來是這樣的：

module Kernel 
    undef_method :rand, :srand 
    class << self 
    undef_method :rand, :srand 
    end 
end 

class Random 
    undef_method :rand, :srand, :seed 
    class << self 
    undef_method :rand, :srand, :new 
    end 
end

來源

2016-04-07 15:19:18

在Array類中禁用隨機播放和樣本

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