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zellyn

I'm new to Kotlin. Can someone explain how this function creates a Money object incorporating the given count of them?

This looks like it's ignoring the Number and creating a new Money object (of denomination 1?)

> public infix fun Number.money(currency: String): Money = money(currency, defaultRoundingMode, null)

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In Kotlin, an infix method can be called without the `.` operator, and without the parens surrounding arguments.

    100 money "USD"

is the same as

    100.money("USD")

`Number.money(currency: String): Money` is an extension method; Kotlin provides syntactic sugar which allows you to "add" methods to existing classes. The above is basically equivalent to:

    fun money(count: Number, currency: String): Money

Thanks!

I allowed myself to be distracted by all the weird infix stuff. I was thinking "but it's not passing itself into the money constructor" but it's actually just delegating to a different-signature version of `money` _on itself_ that will use its value then.

Great see that kotlin didn't avoid all Scala's bad ideas.

It'd be easier to follow if you could provide a link to the GitHub line you're looking at, but most likely the `money` function being called is a second extension method of the Number class, which means that it implicitly gets the Number object as `this` and presumably uses it to build the Money.

https://github.com/eriksencosta/money/blob/4bef95a1d2158e308...

Yeah, that's just an infix function that provides some default parameters to this extension method:

https://github.com/eriksencosta/money/blob/4bef95a1d2158e308...

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