Since default arguments are not supported you can get a similar behavior using Option<T> fn add(a: Option<i32>, b: Option<i32>) -> i32 { a.unwrap_or(1) + b.unwrap_or(2) } This accomplishes the objective of having the default value and the function coded only once (instead of in every call), but is of course a whole lot more to … Read more
You can specify multiple binaries using [[bin]], as mentioned here: [[bin]] name = “daemon” path = “src/daemon/bin/main.rs” [[bin]] name = “client” path = “src/client/bin/main.rs” Tip: If you instead put these files in src/bin/daemon.rs and src/bin/client.rs, you’ll get two executables named daemon and client as Cargo compiles all files in src/bin into executables with the same … Read more
At the basic level, there’s not much difference, but they’re still there. Haskell describes functions or values defined in a typeclass as ‘methods’, just as traits describe OOP methods in the objects they enclose. However, Haskell deals with these differently, treating them as individual values rather than pinning them to an object as OOP would … Read more
Clone is designed for arbitrary duplications: a Clone implementation for a type T can do arbitrarily complicated operations required to create a new T. It is a normal trait (other than being in the prelude), and so requires being used like a normal trait, with method calls, etc. The Copy trait represents values that can … Read more
To convert a slice of bytes to a string slice (assuming a UTF-8 encoding): use std::str; // // pub fn from_utf8(v: &[u8]) -> Result<&str, Utf8Error> // // Assuming buf: &[u8] // fn main() { let buf = &[0x41u8, 0x41u8, 0x42u8]; let s = match str::from_utf8(buf) { Ok(v) => v, Err(e) => panic!(“Invalid UTF-8 sequence: {}”, … Read more
TL;DR: One can instead use &str, &[T] or &T to allow for more generic code. One of the main reasons to use a String or a Vec is because they allow increasing or decreasing the capacity. However, when you accept an immutable reference, you cannot use any of those interesting methods on the Vec or … Read more
As you may have noticed, Rust does not have exceptions. It has panics, but their use for error-handling is discouraged (they are meant for unrecoverable errors). In Rust, error handling uses Result. A typical example would be: fn halves_if_even(i: i32) -> Result<i32, Error> { if i % 2 == 0 { Ok(i / 2) } … Read more
Cargo passes some metadata to the compiler through environment variables, a list of which can be found in the Cargo documentation pages. The compiler environment is populated by fill_env in Cargo’s code. This code has become more complex since earlier versions, and the entire list of variables is no longer obvious from it because it … Read more
In Rust 1.3.0 and later, join is available: fn main() { let string_list = vec![“Foo”.to_string(),”Bar”.to_string()]; let joined = string_list.join(“-“); assert_eq!(“Foo-Bar”, joined); } Before 1.3.0 this method was called connect: let joined = string_list.connect(“-“); Note that you do not need to import anything since the methods are automatically imported by the standard library prelude.
None of the functions I show here panic on their own, but I am using expect because I don’t know what kind of error handling will fit best into your application. Go read The Rust Programming Language‘s chapter on error handling to understand how to appropriately handle failure in your own program. Rust 1.26 and … Read more