When to Use Type Methods

“Type methods are similar to type properties. Use a type method when the action is related to the type, but not something that a specific instance of the type should perform.

Can some please explain this statement with a simple example?

It comes down to the difference between a type and an instance of that type.

I always explain it as the difference between a biscuit cutter and a biscuit.

The biscuit cutter has the pattern for the biscuit.

A type has the "design" of the objects (instances) it is going to create.

Type properties describe how the "biscuit cutter" looks (its shape, material, etc) - type methods are the things that you can do to the "biscuit cutter" (cut biscuit, eject biscuit, clean, etc)

Instance properties describe the "biscuits" (chocolate, wholegrain, soft, hard, etc) - instance methods describe what you can do to a biscuit (eat, crumble, dunk, etc)

Does that help?

1 Like

Perfect comparison.

always start with a type method, then, if you realize the method needs access to the instance, self, “upgrade” it to an instance method. (similar strategy works for func and mutating func)

… and value types vs reference types.

… and let vs var

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