Should I avoid unwrap in production application?

rust unwrap
rust expect

It's easy to crash at runtime with unwrap:

fn main() {

fn c() -> Option<i64> {


   Compiling playground v0.0.1 (file:///playground)
 Running `target/debug/playground`
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', ../src/libcore/
note: Run with `RUST_BACKTRACE=1` for a backtrace.
error: Process didn't exit successfully: `target/debug/playground` (exit code: 101)

Is unwrap only designed for quick tests and proofs-of-concept?

I can not affirm "My program will not crash here, so I can use unwrap" if I really want to avoid panic! at runtime, and I think avoiding panic! is what we want in a production application.

In other words, can I say my program is reliable if I use unwrap? Or must I avoid unwrap even if the case seems simple?

I read this answer:

It is best used when you are positively sure that you don't have an error.

But I don't think I can be "positively sure".

I don't think this is an opinion question, but a question about Rust core and programming.

How do you feel about using expect and unwrap in production code , If you're writing a library, you should avoid doing that in favor of returning errors. unrecoverable errors anyway, so unwrapping would actually be the right thing to do. Workers, as well as significant performance gains in web applications. By doing this, you’ll avoid any surprises in production. For this, you need to have production-like environments. This doesn’t necessarily mean that you’ll have the same data everywhere—that can be expensive and a possible security risk.

In other words, can I say my program is reliable if I use unwrap? Or must I avoid unwrap even if the case seems simple?

I think using unwrap judiciously is something you have to learn to handle, it can't just be avoided.

My rhetorical question barrage would be:

  1. Can I say my program is reliable if I use indexing on vectors, arrays or slices?
  2. Can I say my program is reliable if I use integer division?
  3. Can I say my program is reliable if I add numbers?

(1) is like unwrap, indexing panics if you make a contract violation and try to index out of bounds. This would be a bug in the program, but it doesn't catch as much attention as a call to unwrap.

(2) is like unwrap, integer division panics if the divisor is zero.

(3) is unlike unwrap, addition does not check for overflow in release builds, so it may silently result in wraparound and logical errors.

Of course, there are strategies for handling all of these without leaving panicky cases in the code, but many programs simply use for example bounds checking as it is.

Replacing unwrap() and avoiding panics in Rust, unwrap() is a useful tool in Rust but is also bad practice in production code error case should be communicated back to the application user. To write proper async C# code and avoid deadlocks you need to understand a few concepts. The same async await can be achieved by using ContinueWith and Unwrap. This type of code should be

Avoiding Force Unwrapping in Swift | by Steven Curtis, You might hear that Force Unwrapping is bad and should be avoided at In a real Application, this would mean a full crash, that is in iOS you would find to produce production-ready code you will probably be expected to� Daily production testing gives confidence to the developers that the application runs smoothly and hassle free. Here are some advantages of Testing in Production environment: Monitor the application’s performance in real-time scenarios where the test cases are not predefined, and the user keeps changing data.

unwrap() is not necessarily dangerous. Just like with unreachable!() there are cases where you can be sure some condition will not be triggered.

Functions returning Option or Result are sometimes just suited to a wider range of conditions, but due to how your program is structured those cases might never occur.

For example: when you create an iterator from a Vector you buid yourself, you know its exact length and can be sure how long invoking next() on it returns a Some<T> (and you can safely unwrap() it).

Unwrapping Rust's errors. The Rust programming language is loved , Here's how to effectively deal with Result<>, Error types and unwrap the maze of error handling. If the function returns an Err(error) , the program will stop. types of errors to expose to an end user, as such applications tend to have should be switched to another panic provider on production devices,� If you're just wanting to map something with a tileable texture, Then box mapping, or planar mapping, cylinder, etc Would work without having to unwrap the object.. Also you can unwrap the object like above to avoid texture seams if you don't map the object correctly with a cylinder mapping. Anyways Regardless..

unwrap is great for prototyping, but not safe for production. Once you are done with your initial design you go back and replace unwrap() with Result<Value, ErrorType>.

Killing unwrap() • Dimitri Merejkowsky, will crash with: called Option::unwrap on a None value . This is fine if unwrap() is called in a test, but in production code it's best to prevent� How many Application Insights resources should I deploy. 05/11/2020; 5 minutes to read +1; In this article. When you are developing the next version of a web application, you don't want to mix up the Application Insights telemetry from the new version and the already released version. To avoid confusion, send the telemetry from different

Avoiding force unwrapping in Swift unit tests, So avoiding force unwrapping (when possible) can help us build apps Automatically build, test and distribute your app on every Pull Request make a clear distinction between our testing code and our production code. $\begingroup$ in that case your image is not good for this purpose; you can either keep the same principle (concentric pattern) but you need to make it larger, or create a orthogonal pattern and unwrap in another way, like cylinder or active quad $\endgroup$ – moonboots Jul 26 at 16:01

To unwrap or not to unwrap? - help, However, it does feel somewhat 'dirty' to do so, because you are converting a Now I wonder: In proper application or library code, how are these cases Why avoid unwrap on an option when you are sure that what are you� Sorry to answer my own question, but I have found the cause. I should have posted the entire screen. When I clicked the button left from the "View" button the left bottom and changed it to "UV/Image Editor", the UV unwrap became visible right away, so I would think that the model was indeed unwrapped but not shown.

3ds Max Help: Unwrap UVW Modifier, For example, you can apply Unwrap UVW above a Morpher modifier in the modifier stack, apply planar maps and edit the UVW coordinates. The mapping will� Although the end result should theoretically be the same, you should probably unwrap the base mesh prior to running the simulation. It will be much easier to get a clean UV map with a proper layout from a plain undeformed base mesh then from a wrinkled and highly subdivided result of the physics simulation.

  • Crash is a horribly misused word nowadays IMO; people even use it for an unhandled exception in languages with exceptions. Panicking the program is nowhere near as bad as a segfault, for example. Panicking is deliberately saying "the state of the program is wrong and I'm stopping right now, no two ways about it.
  • @Shepmaster Ok thanks for these precisions!
  • Boom, super clear! I read it carefully and learned a lot! I will keep this in mind: "you can very often restructure your code to avoid the unwrap()!"
  • I'd +1 that answer if it had just one mention of expect().
  • I'd rather he used expect("") stating what he was expecting in the string rather than unwrap() stating what the was expecting in a comment above!
  • I'm not sure about that. Sure, often expect("") is a better choice. But: the user should never see panics anyway. And if the stack trace is already enough for the developer to figure out what the problem is, then it's often enough to simply unwrap(). Also: I'm talking about 4 to 15 lines comments describing exactly why the following unwrap() can't possibly fail. I don't want to type that into a string.
  • I prefer something like .expect("string literal is valid regex") over .unwrap() because it helps to document why unwrapping was chosen originally, which can be important for deciding on the proper fix when multiple cycles of maintenance and refactoring have obscured it. (Not to mention possibly informing the reafactoring so the odds of a problem being introduced are lower.)
  • I personally think unwrap() is dangerous and prevents your code from modification because it needs you to be very careful when editing the code because unwrap() depends on what is written before. Also, you may know some conditions under which some unwrap() may be safe but you must think that these conditions may change some day and that you will need to reread and understand everything that is done before this unwrap. I also think that if you has already written unwrap() it is better to make a comment // safe in these lines. I do this to check how much unwrap do I have with grep.
  • Those conditions may or may not have to change in the future. I'm not saying it's a rule - it's just perfectly possible.
  • unwrap is perfectly safe for production. A process that isn't running is in the safest possible state.