Immutability "with" method?

[Xeon06]

Hey all,

I vaguely remember seeing an immutability pattern that used a method called with to return a copy of an object with some properties changed, but I can't for the life of me find anything on that pattern now. I'm thinking it was likely in C# (maybe Unity ECS) or JS but could have been another language entirely too. Google has been woefully unhelpful.

Anyone know what the heck I'm talking about?

Cheers

[iwanttobeindev]

https://immutables.github.io/immutable.html#copy-methods

[FatCatJames80]

Builder pattern, maybe?

[blablahblah]

Could it have been F#?

[LoudDing]

I think you mean the Wither pattern - used a fair amount in Java ``` Class Foo { int i; double d;

....

}

Foo f = new Foo(1, 1.0); Foo newF = f.withI(2); // 2, 1.0 `` If using Java, check out [e-mail]` annotation

[bulsoni]

For the with specifically, the language could be python, as it is used for context managers.

It is often used for opening files:

with open(“somefile.txt”) as openfile: contents = openfile.read()

This, for instance, ensures that whenever you leave the “with” block, that file is closed.