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PROXY PATTERN - Coggle Diagram

- - - - Introducing another level of complexity. We put a proxy in order to control access to the object
    - - Access remote resources that exists in a different server
        
        This interaction could be wrapped in a proxy, he will interact with the remote server and he will return a promise
    - - Control access to a resource that is expensive to create
        
        We have an object to interact with and creating that object is expensive. So we put something in front to make sure that we will get the object only when we really need it
    - - We have an user and we are not sure if that user have the right to access a particular resource
        
        The protection proxy will make sure that only the allowed user will have the right to access that particular object
- - - - When we pass the string we immediately parse it and after we can use some methods that expose the result of the parse
      - Light operation because the parse has already occur
      - Why not use accessors?
        
        It will indicate to other developers that the field dose not entail computation we would instantly get the value
        
        Properties and Methods should be accessed the same way
    - - Refactor the BookParser in order to implement a lazy load and move the expensive operation when we invoke the methods
      - Use virtual proxy pattern
        
        We can stick a proxy between whoever calls the book parser. And the expensive part can happen only when we call a method LazyLoad
        
        Client
        
        new :check:
        
        Proxy
        
        new :fire:
        
        1 more item...
        
        Call :check: #
        
        The proxy will instantiate the book parser and make the call
        
        We will built it the first time and cache the Book Parser for other calls
        
        Call:check: #
- - - - The book parser
    - - LazyBookParserProxy
      - Has A #
      - The proxy has a Real Subject for controlling the access and the instantiation