Set up a mock database for the sled example
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f9079db520
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@ -756,6 +756,13 @@ dependencies = [
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"libc",
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"libc",
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]
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]
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[[package]]
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name = "error-training"
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version = "0.1.0"
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dependencies = [
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"thiserror",
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]
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[[package]]
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[[package]]
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name = "etcetera"
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name = "etcetera"
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version = "0.8.0"
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version = "0.8.0"
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@ -7,6 +7,7 @@ members = [
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"cyberpunk-splash",
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"cyberpunk-splash",
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"dashboard",
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"dashboard",
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"emseries",
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"emseries",
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"error-training",
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"file-service",
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"file-service",
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"fluent-ergonomics",
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"fluent-ergonomics",
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"geo-types",
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"geo-types",
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1
build.sh
1
build.sh
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@ -10,6 +10,7 @@ RUST_ALL_TARGETS=(
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"cyberpunk-splash"
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"cyberpunk-splash"
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"dashboard"
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"dashboard"
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"emseries"
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"emseries"
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"error-training"
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"file-service"
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"file-service"
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"fluent-ergonomics"
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"fluent-ergonomics"
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"geo-types"
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"geo-types"
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@ -0,0 +1,17 @@
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[package]
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name = "error-training"
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version = "0.1.0"
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edition = "2021"
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# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
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[lib]
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name = "error_training"
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path = "src/lib.rs"
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[[bin]]
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name = "error-training"
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path = "src/main.rs"
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[dependencies]
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thiserror = { version = "1" }
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@ -0,0 +1,62 @@
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use thiserror::Error;
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#[derive(Clone, Debug, Error, PartialEq)]
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pub enum FatalError {
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#[error("Database corruption detected")]
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DatabaseCorruption,
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}
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#[derive(Clone, Debug, Error, PartialEq)]
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pub enum MathError {
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#[error("divide by zero is not defined")]
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DivideByZero,
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#[error("result exceeds maxint")]
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ExceedsMaxint,
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#[error("result exceeds minint")]
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ExceedsMinint,
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}
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#[derive(Clone, Debug, Error, PartialEq)]
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pub enum DatabaseError {
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#[error("value not found")]
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NotFound,
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}
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pub mod sled {
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//! Sled-style error handling is based on Result<Result<Value, LocalError>, FatalError>.
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//! FatalErrors do not get resolved. LocalErrors get bubbled up until they can be handled.
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use super::*;
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use std::collections::HashMap;
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pub struct DB(HashMap<String, i8>);
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impl DB {
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pub fn new(lst: Vec<(String, i8)>) -> Self {
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Self(lst.into_iter().collect::<HashMap<String, i8>>())
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}
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/// Retrieve a value from the database. Throw a fatal error with the "fail" key, but
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/// otherwise return either the value or DatabaseError::NotFound.
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///
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/// ```rust
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/// use error_training::{*, sled::*};
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///
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/// let db = DB::new(vec![("a".to_owned(), 15), ("b".to_owned(), 0)]);
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/// assert_eq!(db.get("fail"), Err(FatalError::DatabaseCorruption));
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/// assert_eq!(db.get("a"), Ok(Ok(15)));
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/// assert_eq!(db.get("c"), Ok(Err(DatabaseError::NotFound)));
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/// ```
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pub fn get(&self, key: &str) -> Result<Result<i8, DatabaseError>, FatalError> {
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if key == "fail" {
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Err(FatalError::DatabaseCorruption)
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} else {
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Ok(self.0.get(key).copied().ok_or(DatabaseError::NotFound))
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}
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}
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}
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pub fn run() {}
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}
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@ -0,0 +1,26 @@
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//! Error handling practice.
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//!
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//! The purpose of this crate is to demonstrate error handling in a couple of different scenarios
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//! so that I have clear templates to refer when doing development, instead of hand-waving or
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//! putting error handling off into the unspecified future.
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//!
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//! I am going to demonstrate error handling in the style of [Error Handling in a
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//! Correctness-Critical Rust Project | sled-rs.github.io](https://sled.rs/errors.html) and in my
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//! reformulation of it using Flow.
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//!
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//! I will also test out additional libraries in the same scenarios:
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//!
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//! - anyhow
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//!
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//! A database exists with some numbers. Mathmatical calculations will be performed on those
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//! numbers. Some calculations are invalid and should fail. In some cases, those should be reported
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//! to the user, and in other cases those can be recovered. Sometimes a calculation needs to be
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//! performed on a value that doesn't exist, which is also a failure. However, sometimes, the
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//! database will detect corruption, wich is fatal and should terminate the "app".
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//!
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//! In these scenarios, the "app" is a top-level function which runs the scenario. This particular
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//! app should never crash, just show where crashes would happen.
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fn main() {
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println!("Hello, world!");
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}
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@ -18,8 +18,6 @@ path = "src/main.rs"
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name = "auth-cli"
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name = "auth-cli"
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path = "src/bin/cli.rs"
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path = "src/bin/cli.rs"
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[target.auth-cli.dependencies]
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[dependencies]
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[dependencies]
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base64ct = { version = "1", features = [ "alloc" ] }
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base64ct = { version = "1", features = [ "alloc" ] }
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build_html = { version = "2" }
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build_html = { version = "2" }
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