I think the knot you are trying to untangle here is what I untied here: https://burntsushi.net/unwrap/ https://burntsushi.net/unwrap/ The issue being addressed

I think the knot you are trying to untangle here is what I untied here: https://burntsushi.net/unwrap/ https://burntsushi.net/unwrap/ The issue being addressed in this thread is that OP says this: > While C++’s std::vector<T>::at() throws an exception which can then be caught and cleanly relayed to the application, a panic!() or an abort() are much more annoying to catch and handle. Moreover, panic!()’s are hiding even in the most innocious places like unwrap() and expect() calls, which in my perception should only be allowed in unsafe code, as they introduce a surface for a denial-of-service attack. This is not a nuanced position separating internal runtime invariants with preconditions and what not, like what you're doing and like what my blog does. This is a blanket statement about the use of `unwrap()` itself, and presumably, all panicking branches. This in turn led to this comment in this thread, to which I responded to as being terrible advice: > That behavior is up to the user. The library should only report the error. This is an extreme position and it seems to be advocated by several people in this thread. Yet nobody can point to real examples of this philosophy. Someone did point out sqlite, libavcodec, lmdb and zlib as having error codes that suggest this philosophy is employed, but actually looking at the code in question makes it clear that for most internal runtime invariants, the C library just gets UB. In contrast, Rust will usually prefer panics for the same sorts of broken invariants (like out-of-bounds access). The bottom line here is that I perceive people are suggesting an inane philosophy to dealing with internal runtime invariants. And that instead of going back-and-forth in abstraction land trying to figure out what the fuck other people are talking about, I think it's far more efficient for people to provide concrete examples of real code used by real people that are following that philosophy. If the philosophy being suggested has no real world examples and isn't even followed by the person suggesting it, then the certainty with which people seem to put this philosophy forward is completely unwarranted. Asking for real world examples is a shortcut to cutting through all this confusing language for trying to describe the circumstances that can lead to aborts, panics or UB. (Hence why my blog I linked earlier in this comment is so long.) It's my way of trying to get to the heart of the matter and show that these pithy comments are probably not suggesting what you think they're suggesting. I've written hundreds of thousands of lines of Rust over the years. Many of my libraries are used in production in a variety of places. All of those libraries use `unwrap()` and other panicking branches liberally. And this isn't just me. Other ecosystem libraries do the same thing, as does the standard library.