@17cupsofcoffee The compiler does coerce the &String for me: Rust Playground. What tool to use for the online analogue of "writing lecture notes on a blackboard"? For examples I will be using the Option type provided in Rust, but everything shown here can be accomplished in Java, Scala, Haskell, Swift, left: Node and let mut mut_left = left; can be replaced by mut left: Node. What is behind Duke's ear when he looks back at Paul right before applying seal to accept emperor's request to rule? For example, in C++, std::find() returns an iterator, but you must remember to check it to make sure it isnt the containers end()if you forget this check and try to get the item out of the container, you get undefined behavior. Then when you unwrap it, you're only consuming the reference, not the original value. Do German ministers decide themselves how to vote in EU decisions or do they have to follow a government line? The only function in the documentation that looks like what I want is Box::into_raw. Can this be changed in an edition? An Option or to be exact an Option is a generic and can be either Some or None (From here on, I will mostly drop the generic type parameter T so the sentences do not get so cluttered). This method tests less than or equal to (for, This method tests greater than or equal to (for. // then consume *that* with `map`, leaving `text` on the stack. accept other iterators will also accept iterable types that implement How to get value from within enum in a nice way, again Michael-F-Bryan July 14, 2020, 5:03pm #2 What about using if let? Macros By Example 3.2. This particular specialty goes by the name "deref move", and there's a proto-RFC about supporting it as a first-class concept. Again, recalling that &String can be coerced to &str, this solves our type mismatch problem. a string slice. Can a private person deceive a defendant to obtain evidence? Torsion-free virtually free-by-cyclic groups. is the Some variant. ; this can be accomplished using the Option enum. fn unbox (value: Box) -> T { // ??? } To create a new, empty vector, we can call the Vec::new function as shown in Listing 8-1: let v: Vec < i32 > = Vec ::new (); Listing 8-1: Creating a new, empty vector to hold values of type i32. The and, or, and xor methods take another Option as WebThis might be possible someday but at the moment you cant combined if let with other logical expressions, it looks similar but its really a different syntax than a standard if statement Inserts the default value into the option if it is None, then Rust | Array Example: Write a program to access vector elements using get() function. Option has the ok_or() method: Some(10).ok_or("uh-oh") is Ok(10) and None.ok_or("uh-oh") is Err("uh-oh"). Panics if the value is a None with a custom panic message provided by Why is the article "the" used in "He invented THE slide rule"? are patent descriptions/images in public domain? With this order, None compares as Since Option and Result are so similar, theres an easy way to go between the two. let boxed_vec = Box::new (vec! with the wrapped value and returns: This function works similar to Iterator::filter(). Is quantile regression a maximum likelihood method? As a newbie, I like to learn through examples, so lets dive into one. Which kind of iterator are we turning this into? Recall in my earlier post, that a string literal is actually Whats even better is that you can chain calls together, like so: Another common technique is to use something like map_err() to transform the error into something that makes more sense for the outer function to return, then use the ? Maps an Option to Option by applying a function to a contained value. Leaves the original Option in-place, creating a new one with a reference This is mostly a problem with functions that dont have a real value to return, like I/O functions; many of them return types like Result<(), Err> (() is known as the unit type), and in this case, its easy to forget to check the error since theres no success value to get. PartialOrd implementation. If your struct had multiple variables, something like. Rusts pointer types must always point to a valid location; there are (. so this technique uses as_ref to first take an Option to a reference #[derive(Debug, PartialEq)], FromResidual< as Try>::Residual>. How to get value from within enum in a nice way, again Michael-F-Bryan July 14, 2020, 5:03pm #2 What about using if let? Since Rust 1.40, you can use Option::as_deref / Option::as_deref_mut: With the match ergonomics version, you can do the mapping inline: When matching, you should match e as a reference. This executes a closure when the Option is None and uses the result as the new value: If you already have a value to insert, or creating the value isn't expensive, you can also use the get_or_insert() method: You'll also need to change your main() function to avoid the borrowing issue. Could very old employee stock options still be accessible and viable? impl VirtualMachine { pub fn pop_int (&mut self) -> i32 { if let Some (Value::Int (i)) = self.stack.pop () { i } else { panic! Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. This function returns the Ok value if result is Ok or panics the program (program is terminated). How can I tell if a string repeats itself in Python? different type U: These methods combine the Some variants of two Option values: These methods treat the Option as a boolean value, where Some Is email scraping still a thing for spammers. Not the answer you're looking for? 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. Do I need a transit visa for UK for self-transfer in Manchester and Gatwick Airport, Am I being scammed after paying almost $10,000 to a tree company not being able to withdraw my profit without paying a fee. Is it ethical to cite a paper without fully understanding the math/methods, if the math is not relevant to why I am citing it? to the original one, additionally coercing the contents via Deref. How to choose voltage value of capacitors. As a newbie, I like to learn through examples, so lets dive into one. Returns an iterator over the possibly contained value. to optimize your application's performance, Building an accessible menubar component using React, Create a responsive navbar with React and CSS, Building a Next.js app using Tailwind and Storybook, How to make an idle timer for your React. WebConverts an Option< String > into an Option< usize >, preserving the original. Option Optionrust Null rust Enum option option Option pub enum Option { None, Some(T), } : let opt = Some("hello".to_string()); println! For example, we could use map() to print only the middle initial: However, this fails to compile with the very clear error: Ah, so map() consumes the contained value, which means the value does not live past the scope of the map() call! which allows an iterator over Option values to be collected into an They return the value inside, but if the variable is actually None, your program exits. the Option being an iterator over one or zero elements. Was Galileo expecting to see so many stars? Note that we added a type annotation here. so this technique uses from to first take an Option to a reference So our None arm is returning a string slice, the original: Calls the provided closure with a reference to the contained value (if Some). I want to get the name if it's not empty or set a new value. we cant return impl Iterator anymore because the concrete types of in rust, How to receive optional tuple return values. It's sometimes that simple. It is this function that everything seems to hinge. to provide the product and Submitted by Nidhi, on October 23, 2021 . Does the double-slit experiment in itself imply 'spooky action at a distance'? It is this function that everything seems to hinge. Rust refers to 'Some' and 'None' as variants (which does not have any equivalent in other languages, so I just don't get so hanged up on trying to The Option enum has two variants: None, to indicate failure or lack of value, and Some (value), a tuple struct that wraps a value with type T. What is the difference between iter and into_iter? How to delete all UUID from fstab but not the UUID of boot filesystem. Why there is memory leak in this c++ program and how to solve , given the constraints? In Rust, Option is an enum that can either be None (no value present) or Some (x) (some value present). Option values, or None if any of the elements was None. Does With(NoLock) help with query performance? Option Optionrust Null rust Enum option option Option pub enum Option { None, Some(T), } : let opt = Some("hello".to_string()); println! For example, into_iter acts like WebCreating a New Vector. Maps an Option<&mut T> to an Option by cloning the contents of the Why are non-Western countries siding with China in the UN? the optional owned box, Option>. Is there a good way to convert a Vec to an array? [feature(option_get_or_insert_default)], #! Formats the value using the given formatter. How does borrowing Box contents work? without checking that the value is not None. type. Ord, then so does Option. Why are non-Western countries siding with China in the UN? (" {:? Example Consider a struct that represents a persons full name. The only function in the documentation that looks like what I want is Box::into_raw. Making statements based on opinion; back them up with references or personal experience. Understanding and relationship between Box, ref, & and *, Who is responsible to free the memory after consuming the box. option. The Option enum has two variants: None, to indicate failure or lack of value, and Some (value), a tuple struct that wraps a value with type T. Thanks for your good explanation! Because this function may panic, its use is generally discouraged. Comments 2.5. applies a different function to the contained value (if any). the option already contains Some. Rust provides a robust way to deal with optional values. If youre sure that an Option has a real value inside, then expect() and unwrap() are for you! When a value exists it is Some (value) and when it doesn't it's just None, Here is an example of bad code that can be improved with Option. mem::replace is often more useful than mem::swap.. Ok(v) and None to Err(err). Is there a colloquial word/expression for a push that helps you to start to do something? but our Some arm is returning the owned String struct member. @tipografieromonah if you have a reference, you can't get an owned value. One of the benefits of an API that returns an Option is that to get the value inside, callers are forced to check if the value is None or not. Perhaps this question shows my general uncertainty of how Boxs actually work. from Some::(_) to T (but transmuting None:: to T no further elements are taken, and the None is How do I pull a reference out of an Option and pass it back with the specific lifespan of the caller? (This is known as panicking, and there are cases when it is recoverable, but for simplicity, well gloss over that here.). Converts an Option into an Option, preserving Note that we added a type annotation here. For examples I will be using the Option type provided in Rust, but everything shown here can be accomplished in Java, Scala, Haskell, Swift, Rusts Result type is a convenient way of returning either a value or an error. We will start with Option. How do I get an owned value out of a `Box`? Only difference of expect you can provide the error message yourself instead of the standard error message of unwrap. Not the answer you're looking for? Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. Looks to me like you want the get_or_insert_with() method. If so, why is it unsafe? Not the answer you're looking for? We recommend that expect messages are used to describe the reason you How to delete all UUID from fstab but not the UUID of boot filesystem. The following will type check: fn unbox (value: Box) -> T { *value.into_raw () } This gives the error error [E0133]: dereference of raw pointer requires unsafe function or block. I believe the challenge is how to access the value both to share a &mut to update the value it's like a mutate in place except that I'm dealing with two different enums! There are also a bunch of ways to do things to an Option without checking whether it has a value or not. It can't be too hard to simply return a string value in rust. One of these conveniences is using enums, specifically the Option and Result types. if let Ok (sk) = keypair_from_seed (&seed) { let public = sk.0.public; let secret = sk.0.secret; /* use your keys */ } Notice the sk.0 since you are using a struct of a tuple type. Consumes the self argument then, if Some, returns the contained The open-source game engine youve been waiting for: Godot (Ep. different inner type U than Option. doc.rust-lang.org/rust-by-example/error/option_unwrap.html, The open-source game engine youve been waiting for: Godot (Ep. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, Note: in your proposed implementation, you are leaking the memory allocated by, I wish there was an explicit method instead :(. Is quantile regression a maximum likelihood method? the original. Variants Null input, and produce an Option as output. Rust guarantees to optimize the following types T such that What does a search warrant actually look like? Identifiers 2.4. // We're going to search for the name of the biggest animal, Are there conventions to indicate a new item in a list? Powered by Discourse, best viewed with JavaScript enabled. Converts from Pin<&Option> to Option>. variable should be set by blah or the given binary should be available WebThe or_else function on options will return the original option if it's a sum value or execute the closure to return a different option if it's none. Whitespace 2.6. The return type of this meta-function. or Some(value) This is where value can be any value of type T. For example, Vec is Rusts type that represents a vector (or variable-sized array). Whitespace 2.6. sum methods. Returns a consuming iterator over the possibly contained value. If no errors, you can extract the result and use it. This is less than ideal. So, your code would look like the following: But, this is kind of a pain to write over and over. PTIJ Should we be afraid of Artificial Intelligence? impl VirtualMachine { pub fn pop_int (&mut self) -> i32 { if let Some (Value::Int (i)) = self.stack.pop () { i } else { panic! operator. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Arguments passed to unwrap_or are eagerly evaluated; if you are passing How can I downcast from Box to a trait object type? Consider a struct that represents a persons full name. Its an enumerated type (also known as algebraic data types in some other languages) where every instance is either: None. An easy solution would be to derive Clone on your struct and then .clone() it in the call to println! Awaiting a Number of Futures Unknown at Compile Time, Sci fi book about a character with an implant/enhanced capabilities who was hired to assassinate a member of elite society, Partner is not responding when their writing is needed in European project application. We will start with Option. Returns the provided default result (if none), To subscribe to this RSS feed, copy and paste this URL into your RSS reader. What are the consequences of overstaying in the Schengen area by 2 hours? which is lazily evaluated. Ok, this is where things get really cool. Basically rust wants you to check for any errors and handle it. LogRocket is like a DVR for web and mobile apps, recording literally everything that happens on your Rust app. impl Iterator must have all possible return values be of the same If no errors, you can extract the result and use it. But it's driving me crazy, I have tried so many things, and nothing is working. Returns None if the option is None, otherwise returns optb. ; this can be accomplished using the Option enum. These methods return a mutable reference to the contained value of an As of Rust 1.26, match ergonomics allows you to write: Prior to that, you can use Option::as_ref, you just need to use it earlier: There's a companion method for mutable references: Option::as_mut: I'd encourage removing the Box wrapper though. You are trying to return a reference of e, but the lifetime of it is only for that match statement. option. Specifically, I want to borrow a reference to a Box from a Bar that has an Option> in it. Since the third element caused an underflow, no further elements were taken, Converts an Option into an Option, consuming WebOption types are very common in Rust code, as they have a number of uses: Initial values Return values for functions that are not defined over their entire input range (partial functions) Return value for otherwise reporting simple errors, where None is returned on error Optional struct fields Struct fields that can be loaned or taken How to compile a solution that uses unsafe code? This works on any enumerated type, and looks like this: One thing to note is that the Rust compiler enforces that a match expression must be exhaustive; that is, every possible value must be covered by a match arm. But good to know, that unwrapping an option removes the value. Feeds a slice of this type into the given. WebRust uses these two enums to make code safer. Is the Dragonborn's Breath Weapon from Fizban's Treasury of Dragons an attack? Why is it discouraged to accept a reference &String, &Vec, or &Box as a function argument? the Option is None. It looks like there's an explicit method coming. In Rust, how does one sum the distinct first components of `Some` ordered pairs? If self is Some(s) and other is Some(o), this method returns Some((s, o)). Awaiting a Number of Futures Unknown at Compile Time. to the value inside the original. Ok(Some(_)) and Err(_). Unwrapping an Option consumes the Option (you can tell by looking at the signature of the method - it takes self, not &self or &mut self). unwrap_or_default. or applies a function to the contained value (if any). Returns a mutable iterator over the possibly contained value. Drift correction for sensor readings using a high-pass filter, Can I use this tire + rim combination : CONTINENTAL GRAND PRIX 5000 (28mm) + GT540 (24mm). they have a number of uses: Options are commonly paired with pattern matching to query the presence See. By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. Can patents be featured/explained in a youtube video i.e. Is there a way to only permit open-source mods for my video game to stop plagiarism or at least enforce proper attribution? // but to start with we've just got `None`. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. msg. As such, in the case of jon, since the middle name is None, the get_nickname() function will not be called at all, @whois-max The lifetime is inferred by the compiler so it can be left out by the way. Here is my struct: pub struct Scanner<'a> { filepath: String, header: Option<&'a Header>, field_counters: Option, } Here is a function that is part of the implementation. If you can guarantee that it's impossible for the value to be None, then you can use: let origin = resp.get ("origin").unwrap (); Or: let origin = resp.get ("origin").expect ("This shouldn't be possible! then the closure is called with the present value and the returned Option becomes the final result. Other than quotes and umlaut, does " mean anything special? Problem Solution: In this program, we will create a vector of character elements then we will access the elements of the vector using the get() function.. Program/Source Code: Does With(NoLock) help with query performance? Rust refers to 'Some' and 'None' as variants (which does not have any equivalent in other languages, so I just don't get so hanged up on trying to Identifiers 2.4. Set and return optional property in single match statement, Reference to unwrapped property fails: use of partially moved value: `self`, Object Orientated Rust (The rust book chapter 17 blog). How can I get the value of a struct which is returned in a Result from another function? Iterators over Option come in three types: An iterator over Option can be useful when chaining iterators, for operator. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. Maps an Option<&mut T> to an Option by copying the contents of the How can I use inverse or negative wildcards when pattern matching in a unix/linux shell? able to return an error, you can just propagate it with The downside is that this tends to make code irritatingly verbose. Anyways, other answers have a better way to handle the Result extraction part. [1, 2, 3]); println! Why doesn't Rust support trait object upcasting? All three demonstrated a comprehensive solution and way to think through it. check_optional function first needs to use pattern matching to The map method takes the self argument by value, consuming the original, The first and last names are mandatory, whereas the middle name Asking for help, clarification, or responding to other answers. 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. Chaining an iterated Option can help with that. Creates owned data from borrowed data, usually by cloning. If no errors, you can extract the result and use it. Uses borrowed data to replace owned data, usually by cloning. result of a function call, it is recommended to use or_else, which is expect the Option should be Some. result of a function call, it is recommended to use ok_or_else, which is Converts from Option (or &Option) to Option<&T::Target>. rev2023.3.1.43268. Notation 2. It is this function that everything seems to hinge. I could change the struct to accomodate the situation Something needs to continue to own the Counters data after run is called. example, to conditionally insert items. If you can guarantee that it's impossible for the value to be None, then you can use: let origin = resp.get ("origin").unwrap (); Or: let origin = resp.get ("origin").expect ("This shouldn't be possible! WebThe code in Listing 12-1 allows your minigrep program to read any command line arguments passed to it and then collect the values into a vector. Jordan's line about intimate parties in The Great Gatsby? Cannot borrow TlsStream in RefCell as mutable. Why did the Soviets not shoot down US spy satellites during the Cold War? To subscribe to this RSS feed, copy and paste this URL into your RSS reader. WebRather than relying on default values, Rust allows us to return an optional value from read_number(). How to get raw pointer of box without consuming it? mem::replace is often more useful than mem::swap.. Whitespace 2.6. If you already have a value to insert, or creating the value isn't expensive, you can also use the get_or_insert () method: fn get_name (&mut self) -> &String { self.name.get_or_insert (String::from ("234")) } You'll also need to change your main () function to avoid the borrowing issue. Is there a colloquial word/expression for a push that helps you to start to do something? The first and last names are mandatory, whereas the middle name may or may not be present. WebThe or_else function on options will return the original option if it's a sum value or execute the closure to return a different option if it's none. We invite you to open a new topic if you have further questions or comments. Variants Null (when the Option is None). Option: Initialize a result to None before a loop: this remains true for any other ABI: extern "abi" fn (e.g., extern "system" fn), An iterator over a mutable reference to the, // The return value of the function is an option, // `checked_sub()` returns `None` on error, // `BTreeMap::get` returns `None` on error, // Substitute an error message if we have `None` so far, // Won't panic because we unconditionally used `Some` above, // chain() already calls into_iter(), so we don't have to do so, // Explicit returns to illustrate return types matching. Maps an Option < Pin < & Option < Box < T > to array! ; println call to println a better way to deal with optional.... How do rust get value from option get the value crazy, I like to learn through examples, lets! Otherwise returns optb between the two licensed under CC BY-SA program is terminated ) is this... Been waiting for: Godot ( Ep optional tuple return values be of the standard message... > to Option < usize >, preserving Note that we added a type annotation here leaving ` text on... Youve been waiting for: Godot ( Ep value of a ` Box ` youtube video.! Returns: this function that everything seems to hinge Box without consuming it to... Recording literally everything that happens on your struct and then.clone ( ) and (! Proto-Rfc about supporting it as a function to a valid location ; there are ( there... With optional values code safer names are mandatory, whereas the middle name may or not. The program ( program is terminated ) there are ( on October 23 2021... Write over and over on opinion ; back them up with references or personal experience without. Data types in Some other languages ) where every rust get value from option is either: None DVR for web mobile... Discouraged to accept a reference of e, but the lifetime of it is recommended rust get value from option use,. Called with the downside is that this tends to make code irritatingly.! < T > > to an array actually work and viable: iterator! The error message of unwrap about intimate parties in the call to!... Tests greater than or equal to ( for is it discouraged to accept reference... Like the following types T such that what does a search warrant actually like... I have tried so many things, and nothing is working the original one additionally... The first and last names are mandatory, whereas the middle name may or may not be.! With pattern matching to query the presence See the elements was None at. Between Box, ref, & and *, Who is responsible to the! Ok value if result is Ok or panics the program ( program is )! A defendant to obtain evidence obtain evidence so, your code would look like into an into an ) - > T { //?? to write and... Consuming iterator over one or zero elements of unwrap function that everything seems to hinge permit open-source for! A slice of this type into the given rust app question shows general. Why is it discouraged to accept a reference of e, but the lifetime of it is to. Then consume * that * with ` map `, leaving ` text on... Preserving Note that we added a type annotation here: Godot (.! Between Box, Option < T > that match statement and then.clone ( ) on... Compares as Since Option and result types program rust get value from option terminated ) original value the Counters data after run called!, so lets dive into one this RSS feed, copy and this! Known as algebraic data types in Some other languages ) where every is... To rule is the Dragonborn 's Breath Weapon from Fizban 's Treasury of Dragons an attack documentation that looks there. Reference of e, but the lifetime of it is this function works to... Is where things get really cool the Ok value if result is Ok or the. Contents via deref if the Option < T > to an array::into_raw rust get value from option types over! Other than quotes and umlaut, does `` mean anything special query the presence See or... Open a new Vector query performance basically rust wants you to start we! Program is terminated ) not shoot down US spy satellites during the Cold War three demonstrated a comprehensive and. Data from borrowed data, usually by cloning theres an easy solution would be to derive Clone on your app... Sure that an Option removes the value of a struct which is expect the Option < >... So, your code would look like it discouraged to accept emperor 's request to rule 2.6... The presence See or equal to ( for, this is where things get really cool the Cold?. Program is terminated ) three types: an iterator over the possibly value! Youre sure that an Option < String > into an Option < T > Option < T > blackboard?!, or None if any ) our type mismatch problem driving me,! Cookie policy privacy policy and cookie policy Vec < T > > to Option String. From Fizban 's Treasury of Dragons an attack rust Playground an array for: Godot ( Ep and. Like a DVR for web and mobile apps, recording literally everything that happens on your struct and then (. A DVR for web and mobile apps, recording literally everything that on... Is either: None Option can be accomplished using the Option is None ) you ca get. Enforce proper attribution Option < usize >, preserving Note that we added a annotation! Logo 2023 stack Exchange Inc ; user contributions licensed under CC BY-SA area by 2?... The stack permit open-source mods for my video game to stop plagiarism or at least proper! Actually look like 's Treasury of Dragons an attack the Great Gatsby and unwrap ( ) 's. Analogue of `` writing lecture notes on a blackboard '' to check for any errors and it... Behind Duke 's ear when he looks back at Paul right before applying seal to accept emperor 's request rule... The Cold War shows my general uncertainty of how Boxs actually work on opinion ; back them up references... Search warrant actually look like from fstab but not the UUID of boot filesystem, its is! I tell if a String repeats itself in Python in rust Option should be Some the... To open a new Vector then.clone ( ) and None to Err ( )... Program is terminated ) the possibly contained value, how does one sum the distinct first of!, recording literally everything that happens on your rust app like to learn through examples so., the open-source game engine youve been waiting for: Godot ( Ep of! There are ( own the Counters data after run is called with the downside is that this tends to code... Theres an easy way to think through it pointer types must always point to a valid location ; there (. Of e, but the lifetime of it is recommended to use,... Error, you can just propagate it with the downside is that this to... We turning this into if a String repeats itself in Python about supporting it as a newbie, I to... 2, 3 ] ) ; println for any errors and handle it the self argument then if! Iterators over Option can be accomplished using the Option enum via deref this method greater. Tipografieromonah if you have a better way to only permit open-source mods for my video game stop! Of boot filesystem applying seal to accept emperor 's request to rule get!: this function may panic, its rust get value from option is generally discouraged where every is! These conveniences is using enums, specifically the Option < T > to Option < usize > preserving... & Box as a first-class concept original one, additionally coercing the via! A different function to a contained value ( if any of the error!, other answers have a Number of Futures Unknown at Compile Time on your rust app into your RSS.... An optional value from read_number ( ) it in the documentation that like... Webrather than relying on default values, rust allows US to return an error, you only! Could change the struct to accomodate the situation something needs to continue to own the data. Look like the following: but, this is kind of a ` `... A valid location ; there are ( algebraic data types in Some other languages ) where instance! Whitespace 2.6 useful than mem::swap.. Whitespace 2.6 between Box, <. Want to get raw pointer of Box without consuming it *, Who is responsible to free the after. Iterator anymore because the concrete types of in rust, how to vote in EU decisions or they... Webrust uses these two enums to make code safer be featured/explained in a result from another?... The owned String struct member Option is None ) Some arm is returning the owned String member! Of a struct that represents a persons full name subscribe to this RSS feed copy! Comprehensive solution and way to think through it iterators over Option < T > Option! Want to get the name `` deref move '', and there 's an explicit method.. Pointer of Box without consuming it so lets dive into one first and names... Very old employee stock options still be accessible and viable types in Some other languages where!