scala/scala

Discord is now Scala’s main chat platform. Please join us at https://discord.com/invite/scala

Gavin Bisesi

@Daenyth

Setters?

Daniel Gordon

@DanielGGordon

yeah maybe that doesn't make sense

Gavin Bisesi

@Daenyth

yeah

It doesn't so much define getters either, just that the constructor items are public instead of private by default

Ryan Peters

@sloshy

copy lets you do an immutable shallow copy of one case class instance to another so that might be what you are thinking.

Gavin Bisesi

@Daenyth

It gives you equals, hashcode, copy, Product with Serializable, apply, and unapply

Daniel Gordon

@DanielGGordon

I was thinking about the constructor I think

Ryan Peters

@sloshy

i.e. myCaseClass.copy(name = "newName")

Case classes are best whenever you just have "some data with a shape to it", and if you need more control over how that works a class can work better. Usually (95% of the time) I go with case classes because they're so convenient.

Daniel Gordon

@DanielGGordon

Found a summary that said:

apply
unapply
accessor methods are created for each constructor parameter
copy
equals and hashCode
toString

Ryan Peters

@sloshy

I wouldn't know anything about efficiency. I don't think it's an issue until it's an issue for you. Profile and whatnot if you have to.

Daniel Gordon

@DanielGGordon

So in terms of the performance - is it really just a memory overhead? There isn't actually a runtime difference just because the class has more methods?

Ryan Peters

@sloshy

Also while we're here - make all your case classes/objects final. Inheritance with those is kind of wonky sometimes

Daniel Gordon

@DanielGGordon

final means you can't extend it right?

Ryan Peters

@sloshy

yes

They can extend other things like traits - just not each other, I wouldn't recommend it

Martijn Hoekstra

@martijnhoekstra

an instance of a case class probably isn't going to be bigger than one of a "regular" class

at least, I don't know why it should be

AFAIK the state on automatic final of case classes still is that Martin has some use case for extending case classes in the compiler. I wonder if that's still the case for scala 3

Daniel Gordon

@DanielGGordon

Well @martijnhoekstra for example if I just make a class, there are methods you get when you use the case keyword, so isn't it guaranteed you will have a larger memory footprint for the case class? What I'm not sure about, is if this actually translates to each instance of the class having a large footprint or not.

Martijn Hoekstra

@martijnhoekstra

I believe that you will get a bigger memory footprint for the class itself only, which means once per class, not once per instance of a class

I never worried about this before, so I'm not entirely sure

Daniel Gordon

@DanielGGordon

ok in that case it's negligible

Rob Norris

@tpolecat

Instance size is a constant + memory required for fields

methods don't have a per-instance cost

Soren

@srnb_gitlab

I wrote almost 400 lines of my first C++ code ever in the past two days

And oh boy has it made me really appreciate having cats/fs2

What Even Is A Mutex?:tm:

Rob Norris

@tpolecat

Ironically we don't have an answer to that. I need a re-entrant mutex that understands fibers and it's impossible to write one at the moment.

Robert D. Blanchet Jr.

@blanchet4forte

Anyone here use reactive mongo? I'm using it with play and play.json and I'm trying to insert a document but its complaining that it can't find the implicit Json Format for the object I'm trying to insert even though its declared in its companion object that is getting imported

Error:(63, 15) No Json serializer as JsObject found for type co.firstfoundry.lagom.scaladsl.api.mongo.OffsetDocument. Try to implement an implicit OWrites or OFormat for this type.
          .one(offsetDocument))
Error:(63, 15) not enough arguments for method one: (implicit ec: scala.concurrent.ExecutionContext, implicit writer: play.api.libs.json.OWrites[co.firstfoundry.lagom.scaladsl.api.mongo.OffsetDocument])scala.concurrent.Future[reactivemongo.api.commands.WriteResult].
Unspecified value parameter writer.
          .one(offsetDocument))

Robert D. Blanchet Jr.

@blanchet4forte

figured it out.. my implicit was Format but if I change it to OFormat it finds it.

Ichoran

@Ichoran

@srnb_gitlab - Why do you need to write C++ instead of Rust?

And anyway, Java has mutexes also under ever-so-friendly names like ConcurrentReadWriteLock.

Rob Norris

@tpolecat

Need the equivalent for when there are no threads.

Gavin Bisesi

@Daenyth

TIL json number is a Double and will happily round even integral Long values :trollface:

nafg

@nafg

@Daenyth in what context?

Rob Norris

@tpolecat

yes, the 52-bit integers we have all been asking for

Gavin Bisesi

@Daenyth

@nafg in the context of json parsing

Rob Norris

@tpolecat

> 9223372036854775807
9223372036854776000

close enough eh

Gavin Bisesi

@Daenyth

@tpolecat is that the cutoff? Thanks, we want to see how many of our apis ship ids that get broken this way

Bob Glamm

@glammr1

https://en.wikipedia.org/wiki/36-bit

Rob Norris

@tpolecat

Yeah it's IEEE 754 floating point so you get 52 bits of mantissa and 12 bits of exponent. At least in Javascript. I don't know if JSON itself specifies it.

Martijn Hoekstra

@martijnhoekstra

Json specifies arbitrary precision

Rob Norris

@tpolecat

Ok.

nafg

@nafg

@Daenyth parsing it with what?

Gavin Bisesi

@Daenyth

JSON.parse

Martijn Hoekstra

@martijnhoekstra

But stresses that if you want to be interoperable, you probably need to do IEEE or you'll probably have a bad time

Gavin Bisesi

@Daenyth

@tpolecat json doesn't "specify" much

Where communities thrive

People

Repo info

Activity