2022-03-16 02:30:01 +00:00
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= Prototype =
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This is a design pattern where we copy an existing object without making the
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code dependent on their classes.
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The general idea is sometimes we need an exact clone of an object. We cant copy
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the object exactly from the outside, as we dont know the private fields.
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2022-03-16 02:45:01 +00:00
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Therefore, the object can implement a `clone` method to return an exact copy of
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the object. Such an object that implements `clone` is a *prototype*
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== Prototype registry ==
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Some objects are commonly copied, and therefore we can cache them in a
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[[hash_table]] for O(1) lookup, then just call `clone` on the object and return
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the new object.
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== Implementation ==
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Often it only needs to be a method, `clone()` which returns the same type as
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`this`, and just calls `return myObject(this)`.
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== Use case ==
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* when code shouldnt depend on the concrete classes of objects that you need to
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copy
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* Reduce number of subclasses that differ in how their init their subobjects
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