Matlab空对象模式
在空对象模式(Null Object Pattern)中,一个空对象取代 NULL 对象实例的检查。Null 对象不是检查空值,而是反应一个不做任何动作的关系。这样的 Null 对象也可以在数据不可用的时候提供默认的行为。
AbstractObject.m
classdef AbstractObject < handle
methods(Abstract)
operation(~);
end
end
RealObject.m
classdef RealObject < AbstractObject
properties
name
end
methods
function obj = RealObject(name)
obj.name = name;
end
function operation(obj)
disp("This is object " + obj.name + " operation.");
end
end
end
NullObject.m
classdef NullObject < AbstractObject
methods
function operation(~)
disp("This is NullObject");
end
end
end
ObjectFactory.m
classdef ObjectFactory < handle
properties(Constant)
names = ["matlab","pattern","design"];
end
methods(Static)
function res = getObject(name)
if(sum(ObjectFactory.names == name) > 0)
res = RealObject(name);
else
res = NullObject();
end
end
end
end
test.m
obj1 = ObjectFactory.getObject("matlab");
obj1.operation();
obj2 = ObjectFactory.getObject("null");
obj2.operation();
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