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0 pointswredue2y ago0 comments

Sure, but this is also what defer is for.

There isn’t implicitly called destructors because the languages mantra is “no hidden control flow”. RAII et semantics is almost entirely hidden control flow that you just have to “know”.

Lots of people hate when they need to “just know” things to fully parse the code they’re reading.

You’re free to dislike those decisions, of course. Personally, I like the target of no hidden flow.

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3 comments · 1 top-level

bsder2y ago· 2 in thread

I have a love/hate with this.

The big problem with defer/errdefer is that I have no way to mark a function as "This function always needs a defer after it and the compiler needs to yell at me if it doesn't exist."

It's also sometimes really hard to scope your defer/errdefer correctly. You may have to twist your code inside out because defer/errdefer ends at a block scope while your variable may not (via: "break :blk varname;").

This all bites so hard for things like reference counting. The bugs ... the bugs ... <mumbles huddled up in corner>

kprotty2y ago

You can `errdefer/defer if` inside the blk, then x = blk:{}; defer use(x)` outside the block.

bsder2y ago

That wasn't a request for help (I have debugged my reference counts already), but I thank you nonetheless.

You can do as you say, but that winds up being a lot of non-enforced boilerplate. And you can get subtle errors if you miss the defer at the wrong scope (ask me how I know this ... actually, better yet, please don't as it will give me flashbacks :) ). And neither the language nor compiler can help you. This contrasts with, say, Rust where reference counts or locks can be enforced by the compiler and simply never go wrong.

defer/errdefer is obvously vastly better than C. My codebase was painful in C. Zig made it tractable, but it was hardly pleasant.

Unfortunately, I really don't have a good suggestion as to what Zig should do instead. defer/errdefer is a minimum, but it's not clear what a single, better step further actually would be. Most solutions in other languages wind up with RAII and that invokes a nightmare of cascading design decisions through a programming language that Zig very much does not want to follow.

It will be interesting to see where async/await finally lands. I think that will have some component of a "slightly better" solution.

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