From b544898624fb89199d8727c3ed0c5ff51849ebc2 Mon Sep 17 00:00:00 2001 From: Christine Dodrill Date: Sun, 20 Sep 2020 07:03:37 -0400 Subject: [PATCH] blog/TLDR-rust: fix stuff that people reported on Reddit Closes #211 --- blog/TLDR-rust-2020-09-19.markdown | 46 ++++++++++++++++++++++++------ 1 file changed, 37 insertions(+), 9 deletions(-) diff --git a/blog/TLDR-rust-2020-09-19.markdown b/blog/TLDR-rust-2020-09-19.markdown index bde8f30..62253ef 100644 --- a/blog/TLDR-rust-2020-09-19.markdown +++ b/blog/TLDR-rust-2020-09-19.markdown @@ -19,9 +19,9 @@ various patterns used in Rust code. Also I'm happy to introduce Mara to the blog! -[Hey, happy to be here! I'm Mara, I'll interject with side information, -challenge assertions and more! Thanks for inviting -me!](conversation://Mara/hacker) +[Hey, happy to be here! I'm Mara, a shark hacker from Christine's imagination. +I'll interject with side information, challenge assertions and more! Thanks for +inviting me!](conversation://Mara/hacker) Let's start somewhere simple: functions. @@ -371,7 +371,17 @@ that isn't covered here.](conversation://Mara/hacker) ### Lifetimes Rust does garbage collection at compile time. It also passes ownership of memory -to functions as soon as possible. For example: +to functions as soon as possible. Lifetimes are how Rust calculates how "long" a +given bit of data should exist in the program. Rust will then tell the compiled +code to destroy the data from memory as soon as possible. + +[This is slightly inaccurate in order to make this simpler to explain and +understand. It's probably more accurate to say that Rust calculates _when_ to +collect garbage at compile time, but the difference doesn't really matter for +most cases](conversation://Mara/hacker) + +For example, this code will fail to compile because `quo` was moved into the +second divide call: ```rust // rust @@ -432,7 +442,11 @@ file](https://doc.rust-lang.org/cargo/reference/specifying-dependencies.html): eyre = "0.6" ``` -This depends on the crate [anyhow](https://crates.io/anyhow) at version 1.0.x. +This depends on the crate [eyre](https://crates.io/crates/eyre) at version +0.6.x. + +[You can do much more with version requirements with cargo, see more here.](conversation://Mara/hacker) Dependencies can also have optional features: @@ -520,7 +534,10 @@ Rust has three privacy levels for functions: [You can't get a perfect analog to `pub(crate)` in Go, but internal -packages can get close to this behavior.](conversation://Mara/hacker) +packages can get close to this behavior. Additionally you can have a lot +more control over access levels than this, see here +for more information.](conversation://Mara/hacker) ## Structures @@ -598,11 +615,17 @@ more detail about this. ## Enumerations / Tagged Unions Enumerations, also known as tagged unions, are a way to specify a superposition -of one of a few different kinds of values in one type. The main place they are -used in this project is for command line parsing with -[structopt](https://docs.rs/structopt/0.3.14/structopt/). There is no easy +of one of a few different kinds of values in one type. A neat way to show them +off (along with some other fancy features like the derivation system) is with the +[structopt](https://docs.rs/structopt/0.3.14/structopt/) crate. There is no easy analog for this in Go. +[We've actually been dealing with enumerations ever since we touched the Result +type earlier. Result and Option are +implemented with enumerations.](conversation://Mara/hacker) + ```rust #[derive(StructOpt, Debug)] #[structopt(about = "A simple release management tool")] @@ -639,6 +662,11 @@ match cmd { All variants of an enum must be matched in order for the code to compile. +[This code was borrowed from palisade in order to +demonstrate this better. If you want to see these patterns in action, check this +repository out!](conversation://Mara/hacker) + ## Testing Test functions need to be marked with the `#[test]` annotation, then they will