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Visitor Pattern Design PatternVisitor PatternTwo things: add new operation to Operate one object’s attribute member without change its original class structure(in other words, without change origina

Visitor Code SampleVisitor design pattern 1. Add an accept(Visitor) method to the “element” hierarchy 2. Create a “visitor” base class w/ a visit() method for every “element” type 3. Create a “vi

reference by Decorator Design PatternIntent Attach additional responsibilities to an object dynamically. Decorators provide a flexible alternative to subclassing for extending functionality. Client-spe