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动态定义ruby子类,和判断是否定义
rubydymanic_programming
上篇有个标准的定义动态类变量
Ruby代码- class MyClass
- class << self
- attr_accessor :my_constant
- end
- def my_method
- self.class.my_constant = "blah"
- end
- end
-
- p MyClass.my_constant #=> nil
- MyClass.new.my_method
-
- p MyClass.my_constant #=> "blah"
- class MyClass
- class << self
- attr_accessor :my_constant
- end
- def my_method
- self.class.my_constant = "blah"
- end
- end
- p MyClass.my_constant #=> nil
- MyClass.new.my_method
- p MyClass.my_constant #=> "blah"
复制代码 如果类也动态定义,那么子类和module怎么定义进去的
Ruby代码- dynamic_name = "TestEval2"
-
- Object.const_set(dynamic_name, Class.new{def method1() 42 end }})
- dummy2 = eval("#{dynamic_name}")
- puts "dummy2: #{dummy2}"
- dynamic_name = "TestEval2"
- Object.const_set(dynamic_name, Class.new{def method1() 42 end }})
- dummy2 = eval("#{dynamic_name}")
- puts "dummy2: #{dummy2}"
复制代码 Ruby代码- dynamic_name = "SubTestEval2"
-
- SubModule.const_set(dynamic_name, Class.new(TestEval2){def method1() 43 end })
- dummy3 = eval("#{dynamic_name}")
- puts "dummy3: #{dummy3}"
- dynamic_name = "SubTestEval2"
- SubModule.const_set(dynamic_name, Class.new(TestEval2){def method1() 43 end })
- dummy3 = eval("#{dynamic_name}")
- puts "dummy3: #{dummy3}"
复制代码 判断动态类是否存在
Ruby代码- def class_exists?(class_name)
- eval("defined?(#{class_name}) && #{class_name}.is_a?(Class)") == true
- end
-
- class_name = "Blorp"
- class_exists?(class_name)
- => false
-
- class_name = "String"
- class_exists?(class_name)
- => true
- def class_exists?(class_name)
- eval("defined?(#{class_name}) && #{class_name}.is_a?(Class)") == true
- end
- class_name = "Blorp"
- class_exists?(class_name)
- => false
- class_name = "String"
- class_exists?(class_name)
- => true
- define_method定义的方法参数放到哪?
复制代码 Ruby代码
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