67 lines
1.8 KiB
Markdown
67 lines
1.8 KiB
Markdown
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---
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title: "Part 2: Result Type and error handling"
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date: 2020-09-19
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draft: false
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series: ["Starting with rust"]
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tags: ["rust","coding"]
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---
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Today I experimented with the subject of error handling. One of several ways in Rust is the Result type.
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This is an enum that either contains a value for the success case or an error.
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```rust
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use std::string::String;
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#[derive(Debug)]
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struct Person {
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name: String,
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age: i32,
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}
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impl Person {
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fn hello(&self) -> Result<String, &str>{
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if self.name != "" {
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let ret = format!("{} is {} years old.", self.name, self.age);
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Ok(ret)
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} else {
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Err("No name given")
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}
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}
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}
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fn main() {
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let bob = Person {
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name: String::from("Bob"),
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age: 32,
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};
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let res = bob.hello().unwrap(); // will consume the Ok value or panic in case of error
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println!("{:?}", res);
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let mary = Person {
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name: String::from(""),
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age: 30,
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};
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let res1 = mary.hello().unwrap(); // will consume the Ok value or panic in case of error
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println!("{:?}", res1);
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}
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```
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By appending the method unwrap() the returned Result type is unpacked. In the event of an error, unwrap() leads to panic.
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The output looks like this:
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```rust
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Standard Error:
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Compiling playground v0.0.1 (/playground)
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Finished dev [unoptimized + debuginfo] target(s) in 1.05s
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Running `target/debug/playground`
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thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: "No name given"', src/main.rs:33:29
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note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
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Standard Output:
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"Bob is 32 years old."
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```
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I think that's just the beginning. Using the method unwrap() is quick and easy, but usually you would not want your program to quit with a panic on error.
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