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proxy
subject			fact

proxy	has definition A pattern found in which a lightweight object stands in place of a heavyweight object that has the same interface. It transparently loads the heavyweight object when needed
	has antipatterns Instead of using proxy objects, beginner designers often scatter complex code around their application to load objects from databases. A strategy that only works for very small systems is to load the whole database into memory when the program starts.
	has context There may be a time-delay and a complex mechanism involved in creating instances of heavyweight classes.
	has forces You want all the objects in a domain model to be available for programs to use when they execute a system's various responsibilities It is important for many objects to persist from run to run of the same program in a large system it would be impractical for all the objects to be loaded into memory whenever a program starts It would be ideal to be able to program the application as if all the objects were located in memory
	has problem How can you reduce the need to create instances of a heavyweight class? In particular, how can you reduce the need to load large numbers of them from a database or server, when not all of them will be needed? A related problem is this: If you load one object from a database or server, how can you avoid loading all the other objects that are linked to it.
	has references one of the Gang of Four patterns
	has related patterns several patterns that obtain their power from delegating responsibilities to other classes, hence it uses the Delegation pattern
	has solution Create a simpler version of the «HeavyWeight» class. We will call this simpler version a «Proxy». The «Proxy» has the same interface as the «HeavyWeight», so programmers can declare variables without caring whether a «Proxy» or its «HeavyWeight» version will be put in the variable.
	is a subtopic of 6.12 - The Proxy Pattern
	is an instance of design pattern
design pattern	has name
	should be illustrated using a simple diagram
	should be written using a narrative writing style
pattern	should be as general as possible
	should be described in an easy-to-understand form so that people can determine when and how to use it
	should contain a solution that has been proven to effectively solve the problem in the indicated context

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