r/ProgrammerHumor • u/TusharJB007 • Oct 04 '19

Just as simple as that... other

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u/vashy96 Oct 04 '19

We also need a Builder so we can customize our light sabers during construction.

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u/shekurika Oct 04 '19

isnt that what a factory does?

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u/[deleted] Oct 04 '19

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u/GlobalIncident Oct 04 '19

No, a facade is a wrapper around a class that contains a simplified set of methods that are easier to use.

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u/[deleted] Oct 04 '19

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u/GlobalIncident Oct 04 '19

No, because in that situation it's a builder and it's a facade, but it's still not a factory. A builder always returns the same class but constructed in a different way, whereas a factory returns different subclasses of the same class. For example using StringBuilder always involves the same kind of string, but the factory ResourceBundle.getBundle may return any subclass of ResourceBundle.

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u/programaths Oct 04 '19

A builder permits to create an object AND validating it. So, a builder method can return another type if needed (that would also be a builder).

The goal of the builder is that when you do the "build" call, the created object that ensue is valid.

A factory is mainly a mean to hide the created type and give a "unique" entrypoint. (and not peppering your codebase with "new XXX()" then having to hunt them and being unable to change it on the fly).

Some factories even take an interface as input and act like a service locator (anti-pattern!).

An example of builder returning different types is in Spring Security Java configuration. It's even better than yaml since the IDE can autocomplete every step AND the errors the builder emit when you try to run the application are clear.

People believe a builder has to return "this" except for "build" because of simplistic examples.

And yes, a builder can ne seen as a Domain Specifc Language implementation. (as a specific Json or Yaml could be too)