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> Better error handling. There's a few large firms that don't use exceptions in c++. New language with no legacy? Use the Ok/Error/Some/None thing. I think th

> Better error handling. There's a few large firms that don't use exceptions in c++. New language with no legacy? Use the Ok/Error/Some/None thing. I think this is still very much a debatable point. There are disadvantages to exceptions, mostly around code size and performance. But they are still the only error handling mechanism that anyone has found that defaults to adding enough context to errors to actually be useful (except of course in C++, because C++ doesn't like having useful constructs). Rust error handling tends towards not adding any kind of context whatsoever to errors - if you use the default error mechanisms and no extra libraries. That is, if you have a call stack three functions deep that uses `?` for error handling, at the top level you'll only get an error value, you'll have no idea where the value originated from, or any other information about the execution path. This can be disastrous for actually debugging hard to reproduce errors.

mr_00ff00 2y ago
I feel like your last point is the exact issue with exceptions, not rust’s errors. Exceptions are like having “?” on every single line.
- tsimionescu 2y ago
  When an exception happens, you get a stack trace somewhere in your logs (unless you do something really weird). That doesn't always include all the information you'd like (for example, if the error happened in a loop, you don't get info about the loop variable). In contrast, unless you manually add context to the error (or use a library that does something like this for you, overriding the default ? behavior), you won't get any information about where an error occurred at all. Sure, with exceptions, you don't know statically where an exception might happen. But at runtime, you do get the exact information. So, if the error is hard to reproduce, you still have information about where exactly it occurred in those rare occasions where it happened.
  - tialaramex 2y ago
    > When an exception happens, you get a stack trace somewhere in your logs OK, so, if I write the canonical modern C++ Hello World, execute it against an environment where the "standard output" doesn't exist, where does this stack trace get recorded? Maybe it depends on the compiler and standard library implementation somehow? My impression is that in reality C++ just ignores the problem and carries on, so actually there was no stack trace, no logging, it just didn't work and too bad. Unsurprisingly people tasked with making things work prefer a language which doesn't do that.
    - HumanOstrich 2y ago
      How does any other language deal with POSIX standard I/O streams or the lack thereof? Definitely not a C++ or exceptions problem. Which language lets you compile a "Hello, World!" program and then execute it against a non-POSIX-compatible environment and get the correct output... somewhere? If you're executing against a POSIX-compatible environment, then stdin, stdout, and stderr are expected to exist and be configured properly if you want them to work[1]. If you're executing against some other environment, like webassembly or an embedded system, then you'll already (hopefully) be using some logging and error handling approach that sends output to the correct place. Doesn't matter if you're using C, C++, .NET, Rust, Zig, etc. For example, webassembly is an environment without stdio streams. It's your responsibility to make sure there is a proper way to record output, even if it's just a compatibility layer that goes to console.log. [1]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/stdin.html https://pubs.opengroup.org/onlinepubs/9799919799/functions/s...
      - tialaramex 2y ago
        The other languages do not (as my parent claimed) write stacktraces to a log somehow. I suspect that in reality they've ommitted to explain that they're expected to write all the C++ code to make that stacktrace and write it to a log, but once you add those steps you're back to parity with Rust, the Rust programmers can write a stacktrace to a log too. In the specific case of "Hello, World" it's more embarrassing. The Rust Hello World does indeed experience and report errors if there are any, the canonical C just ignores them, as does the C++.

mr_00ff00 2y ago

I feel like your last point is the exact issue with exceptions, not rust’s errors. Exceptions are like having “?” on every single line.

tsimionescu 2y ago
When an exception happens, you get a stack trace somewhere in your logs (unless you do something really weird). That doesn't always include all the information you'd like (for example, if the error happened in a loop, you don't get info about the loop variable). In contrast, unless you manually add context to the error (or use a library that does something like this for you, overriding the default ? behavior), you won't get any information about where an error occurred at all. Sure, with exceptions, you don't know statically where an exception might happen. But at runtime, you do get the exact information. So, if the error is hard to reproduce, you still have information about where exactly it occurred in those rare occasions where it happened.
- tialaramex 2y ago
  > When an exception happens, you get a stack trace somewhere in your logs OK, so, if I write the canonical modern C++ Hello World, execute it against an environment where the "standard output" doesn't exist, where does this stack trace get recorded? Maybe it depends on the compiler and standard library implementation somehow? My impression is that in reality C++ just ignores the problem and carries on, so actually there was no stack trace, no logging, it just didn't work and too bad. Unsurprisingly people tasked with making things work prefer a language which doesn't do that.
  - HumanOstrich 2y ago
    How does any other language deal with POSIX standard I/O streams or the lack thereof? Definitely not a C++ or exceptions problem. Which language lets you compile a "Hello, World!" program and then execute it against a non-POSIX-compatible environment and get the correct output... somewhere? If you're executing against a POSIX-compatible environment, then stdin, stdout, and stderr are expected to exist and be configured properly if you want them to work[1]. If you're executing against some other environment, like webassembly or an embedded system, then you'll already (hopefully) be using some logging and error handling approach that sends output to the correct place. Doesn't matter if you're using C, C++, .NET, Rust, Zig, etc. For example, webassembly is an environment without stdio streams. It's your responsibility to make sure there is a proper way to record output, even if it's just a compatibility layer that goes to console.log. [1]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/stdin.html https://pubs.opengroup.org/onlinepubs/9799919799/functions/s...
    - tialaramex 2y ago
      The other languages do not (as my parent claimed) write stacktraces to a log somehow. I suspect that in reality they've ommitted to explain that they're expected to write all the C++ code to make that stacktrace and write it to a log, but once you add those steps you're back to parity with Rust, the Rust programmers can write a stacktrace to a log too. In the specific case of "Hello, World" it's more embarrassing. The Rust Hello World does indeed experience and report errors if there are any, the canonical C just ignores them, as does the C++.