Consider the following code (or run it in rust playground here): fn main() { let a:Vec = vec![1, 2, 3]; let doubled = a.iter().map(|&x| x * 2).collect(); assert_eq!(vec![2, 4, 6], doubled); } If you ran it in the playground linked above, you will see the following compiler error. error[E0282]: type annotations needed –> src/main.rs:4:9 | […]
Consider the following test code that creates a file, writes to it and then reads back to confirm what it wrote. #[cfg(test)] mod tests { #[allow(unused_imports)] use super::*; use std::fs::{self, File, OpenOptions}; use std::io::{Read, Seek, SeekFrom, Write}; use tempfile::{tempdir, tempfile, NamedTempFile}; #[test] fn test_file() { let dir = tempdir().unwrap(); let file_path = dir.path().join(“foo.txt”); let mut […]
I was looking for Python style temporary files and temporary directories in Rust. Very handy when writing tests for simulating actual files, or when we need to use files once or cache large amount of data for short time. We then let the operating system delete the files at a later time automatically or by […]
I was going through some library code in a rust crate and this pattern had my head scratching: std::io::{self,Cursor}; What this is equivalent to is: use std::io; use std::io::Cursor; which means explicitly use std::io::Cursor and also use std::io itself. Thus, Cursor need not be prefixed but you’d still need to do io::BufReader and so on.
Difference Between Box, Rc, Arc, Cell (and its various variants.. RefCell, Mutex, RwLock) in Rust: Box is for single ownership. A great use case is to use this when we want to store primitive types (stored on stack) on heap. Rc is for multiple ownership. Arc is for multiple ownership, but threadsafe. RefCell is for […]