What's the best way to shorten this code ? All call() methods take and return a list. Is there a way...

# getting-started

[sarvagya agarwal]

What's the best way to shorten this code ? All call() methods take and return a list. Is there a way to chain all these operations ?

var list = serviceA.call(list)
list = serviceB.call(list)
list = serviceC.call(list)
list = serviceD.call(list)

[Kevin Healy]

Make an extension function on the list type that takes a service as a parameter, it could become

list.call(serviceA).call(serviceB).call(serviceC).call(serviceD)

[Casey Brooks]

If they’re all of the same interface, you can do a .fold operation

listOf(
    serviceA,
    serviceB,
    serviceC,
    serviceD,
).fold(initial = emptyList()) { acc, service -> service.call(acc) }

[Klitos Kyriacou]

Casey's idea is great, but it's funny how we consider it a "shortening" when 4 lines get "shortened" to 6 lines.

[Kevin Del Castillo]

What Kevin Healy suggests could also work, only if your services all share the same interface with the call function that receives a list

[Klitos Kyriacou]

@Kevin Del Castillo if they don't share the same interface, it could also work, by overloading the call function.

[Kevin Del Castillo]

That would require four different overloads 😛

[Kevin Del Castillo]

It kinda defies the purpose of shortening the code by adding more hidden code

[Kevin Healy]

mm, I dunno. I'd rather have more verbose code behind an API that enables more fluent code at the call site

[Casey Brooks]

Shortening doesn’t always mean fewer lines of code, but rather shortening the amount of thought needed to understand it. Even though I broke the listOf() down to multiple lines, it’s still only 1 statement which is easily understandable. I tend to break these kinds of lists down because I use IntelliJ’s “duplicate line” feature a lot, and this makes it easier

Really, the snippet is just 1 “line”, or 1 “statement”. The listOf() is just boilerplate, those services could be injected via DI as a list so that wouldn’t necessarily actually be at the point where you do the sequence of .call. So my snippet reduces 4 statements down to 1, but it does require that one understands what the .fold operation is doing to actually make it more understandable

[Kevin Del Castillo]

@Kevin Healy Yeah that depends if the API you're building is meant to be used by a sufficient amount of developers for it to be considered a "public API", medium to big teams would benefit from this as well as library consumers if it's part of a library

[Kevin Healy]

I know it's not always practical, but I think it's good practice to write everything as though it might become a public API even if you're the sole developer; you never know who's going to pick up your code next

[Kevin Del Castillo]

Agree! I think it all boils down to a constant battle between idealism and pragmatism K

[Charles Flynn]

Another flavour of this i’ve used is:

val newList = list
        .let { serviceA.call(it) }
        .let { serviceB.call(it) }
        .let { serviceC.call(it) }
        .let { serviceD.call(it) }