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Specify the kinds of objects to create using a prototypical
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instance, and create new objects by copying this prototype.
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![alt text](./etc/prototype_1.png"Prototype")
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## Explanation
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Real world example
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> Remember Dolly? The sheep that was cloned! Lets not get into the details but the key point here is that it is all about cloning.
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In plain words
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> Create object based on an existing object through cloning.
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Wikipedia says
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> The prototype pattern is a creational design pattern in software development. It is used when the type of objects to create is determined by a prototypical instance, which is cloned to produce new objects.
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In short, it allows you to create a copy of an existing object and modify it to your needs, instead of going through the trouble of creating an object from scratch and setting it up.
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**Programmatic Example**
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In Java, it can be easily done by implementing `Cloneable` and overriding `clone` from `Object`
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```
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class Sheep implements Cloneable {
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privage String name;
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public Sheep(String name) { this.name = name; }
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public void setName(String name) { this.name = name; }
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public String getName() { return name; }
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@Override
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public Sheep clone() throws CloneNotSupportedException {
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return new Sheep(name);
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}
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}
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```
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Then it can be cloned like below
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```
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Sheep original = new Sheep("Jolly");
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System.out.println(original.getName()); // Jolly
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// Clone and modify what is required
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Sheep cloned = original.clone();
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cloned.setName("Dolly");
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System.out.println(cloned.getName()); // Dolly
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```
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## Applicability
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Use the Prototype pattern when a system should be independent of how its products are created, composed and represented; and
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* when the classes to instantiate are specified at run-time, for example, by dynamic loading; or
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* to avoid building a class hierarchy of factories that parallels the class hierarchy of products; or
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* when the classes to instantiate are specified at run-time, for example, by dynamic loading
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* to avoid building a class hierarchy of factories that parallels the class hierarchy of products
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* when instances of a class can have one of only a few different combinations of state. It may be more convenient to install a corresponding number of prototypes and clone them rather than instantiating the class manually, each time with the appropriate state
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* when object creation is expensive compared to cloning
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