I want to get version from Cargo.toml and use the value inside my app. Here is a function I wrote:

use std::fs;

pub fn get_version() -> &'static str {
    let text = fs::read_to_string("Cargo.toml").unwrap();
    for line in text.split("\n") {
        if line.starts_with("version") {
            let start = line.find('"').unwrap() + 1;
            let end = line.rfind('"').unwrap();
            let version = &line[start..end];
            return Box::leak(version.to_string().into_boxed_str());

    panic!("failed parsing version from Cagro.toml");

Writting the function, I had some questions. So I'd like to get help from others.

  • How can I replace for and if nested blocks with iterator methods?
  • To return value as static lifetime, I used Box::leak(version.to_string().into_boxed_str()) which is too complicated (&str -> String -> Box<str> just for avoiding compile errors). How can I return &'static str or &'a str simply without getting cannot return value referencing local variable ... error in this case?
  • Can I make the code simpler? (ex: parsing the version value)
  • 1
    \$\begingroup\$ Do you know about macro env!? \$\endgroup\$
    – aSpex
    Apr 10, 2019 at 14:57
  • \$\begingroup\$ @aSpex Thanks for the information. I can easily get Cargo version via env!. Apart from it, I'd like to get my code reviewed. \$\endgroup\$
    – philipjkim
    Apr 11, 2019 at 1:15


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