RqWithHeaders is not immutable

[2686747]

RqWithHeaders changes after new RqPrint(rqWithHeaders).print(); This test will not pass.

[davvd]

@yegor256 please do something about this issue

[yegor256]

@2686747 it's not a bug. it's by design. this is how it should work. I created a test to confirm that: fb89dde

[2686747]

@yegor256 ok, but what about "immutable"?

[yegor256]

@2686747 immutability doesn't mean that return values are always the same. immutable doesn't mean constant. see http://www.yegor256.com/2014/12/22/immutable-objects-not-dumb.html

[2686747]

@yegor256 good point, but now you have to leave this link everywhere in project's javadocs, because we have Java and wiki. And all is clear here: state doesn't change. And sorry, but when i call print(smth) - i don't expect than print will change this something and i talk not just about immutable now. We're using decorators in each line practically - do i have to check all of them for print(smth)? And i didn't start with a thread-safety yet.

[yegor256]

@2686747 but print() doesn't change anything. it's just an input stream, which works in a non-immutable way. not our object. we just return an input stream. how it behaves - not our area of responsibility. see?

[2686747]

@yegor256 I understand completely but why i have to worry about implementation of some object? I don't see InputStream, i see Request which is marked as immutable and thread-safe. And of course i expect it won't change after some external method execution, especially such harmless as print() . And if it's impossible we have to remove all "immutable and thread-safe" and leave very clear attention in javadocs

[yegor256]

@2686747 you just misunderstand what "immutable and thread-safe" means. you think they mean "constant", while it's not true. the problem is in your understanding, not in our texts :)

[2686747]

@yegor256 please, reread this smart man )))

[yegor256]

@2686747 yeah, I read that dude, a few times :) check this out: http://www.yegor256.com/2014/12/09/immutable-object-state-and-behavior.html

[2686747]

@yegor256 how is your own example with side effect different from RqPrint(request).print() (except syntax of course)?

[yegor256]

@2686747 we're dealing with a mutable InputStream here, that's why we inevitably have that side effect. we can't get rid of it, without breaking the entire idea of mutable input streams in Java. blame Java, not us :)