rustUsing error chain in Rust

Error chain is a Rust library for creating and managing error types and error handling. It provides a convenient way to define and propagate errors throughout a Rust program.

Code example:

use error_chain::error_chain;

error_chain! {
    foreign_links {
        Io(std::io::Error);
        ParseInt(std::num::ParseIntError);
    }
}

fn main() -> Result<()> {
    let result = std::fs::read_to_string("my_file.txt")?;
    let number = result.parse::<i32>()?;
    println!("Number is {}", number);
    Ok(())
}

Output

Number is 42

Explanation:

1. The error_chain! macro is used to define the error types and foreign links.
2. The foreign_links section defines the external errors that can be propagated through the error chain. In this example, std::io::Error and std::num::ParseIntError are defined as foreign links.
3. The main function is used to read a file and parse its contents as an integer.
4. The std::fs::read_to_string function is used to read the contents of the file into a string. The ? operator is used to propagate any errors that occur during the read operation.
5. The parse::<i32> method is used to parse the string as an integer. The ? operator is used to propagate any errors that occur during the parse operation.
6. The parsed integer is printed to the console.
7. The Ok(()) expression is used to indicate that the function has completed successfully.

Helpful links:

1. Error Chain Documentation
2. Rust Error Handling Tutorial

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