• @[email protected]
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    1611 months ago

    What’s the point of having friends when the whole point of private fields is to ensure that you don’t break other parts when changing those?

    • @NightAuthor
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      1511 months ago

      It’s just another option, don’t gotta use it. Maybe you find yourself needing something like this, and the only other choice is making it public. At least with friend classes, you know which classes are friends so you can go look for any dependencies

      • @[email protected]
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        411 months ago

        It’s just another option, don’t gotta use it

        It’s not a choice of mine when I’m trying to read through / modify some legacy code base

    • Codex
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      911 months ago

      There’s infinite ways to organize code. In C# or Rust where this isn’t an option, you might use nested classes or traits hidden behind a module/namespace.

      Good use cases are data structures with associated helper classes. For example, a collection/tree and an iterator/tree-walker for working with elements of the collection. Or for something like a smart memory allocator (an arena or slab allocator), you might use a friend-class to wrap elements returned from the allocator, representing their connection back to it (for freeing up when done or to manage the allocation structure in ie a heap or sorted tree).

  • Ziglin (they/them)
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    611 months ago

    Does C++ actually have something like that? That sounds like something made up for the joke?

      • Ziglin (they/them)
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        11 months ago

        Huh, do Java and other oop languages have them too and what are some good reasons to use them?

        • UnfortunateShort
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          311 months ago

          It allows for more fine grained access control and to implement afterthoughts.

          Think having some private function that can break things if called improperly, but also allow you to avoid significant overhead when calling it the correct way. For example you could be avoiding input validation in a public wrapper for that function. If your friendly class already does it, or cannot produce invalid inputs, there is no need for that.

          You could also implement logging after the fact, because your friendly logger object to read private members.

          Arguably it’s a questionable design decision tho, as you could do all of this in other ways and it basically breaks any guarantees private would usually give you.

          • Ziglin (they/them)
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            111 months ago

            That was a problem I saw with it but I guess it’s useful too. I like structs.