我想知道如何在另一个类的类实例中调用方法.
这就是我提出的
class ClassA
def method
return "This is a method_from_class_A"
end
end
class ClassB
def initialize
@method_from_class_A=instance.method
end
def method_calls_method
@method_from_class_A
end
end
instance=ClassA.new
instance2=ClassB.new
puts instance2.method_calls_method
但我得到这个错误：
Testing.rb:9:in
initialize': undefined local variable or methodinstance’ for # (NameError) from
Testing.rb:19:innew' from Testing.rb:19:in‘
我该怎么办呢？
感谢您的答复.
解决方法
根据你的描述,这似乎是你想要的：
class ClassB
def initialize
@instance_of_class_a = ClassA.new
end
def method_calls_method
@instance_of_class_a.method
end
end
或者传入ClassA实例(这称为依赖注入)：
class ClassB
def initialize(class_a_instance)
@instance_of_class_a = class_a_instance
end
def method_calls_method
@instance_of_class_a.method
end
end
instance_a = ClassA.new
instance_b = ClassB.new(instance_a)
puts instance_b.method_calls_method