Julia 1.0 Programming Complete Reference Guide

Inner constructors

The external constructor (where we invoke the type as a function) is a default constructor where we provide the values for all the fields, in the right order—and get back an instance of the corresponding type. But, what if we want to provide additional constructors, that maybe impose certain constraints, perform validations, or are simply more user-friendly? For this purpose, Julia provides internal constructors. I've got a good use case for them.

I'm not especially fond of our Article constructor—it takes too many arguments that need to be passed in the exact right order. It's hard to remember how to instantiate it. We've learned earlier about keyword arguments—and it would be awesome to provide an alternative constructor ...