Use eyre for error handling

`Box<dyn Error>` is not `Send`, which makes it harder to parallelize the rendering of the blog posts. `eyre::Report` fortunately does not have this problem.

Author: Turbo87

Cargo.lock

@@ -9,6 +9,7 @@ name = "blog"
 path = "src/blog.rs"
 
 [dependencies]
+eyre = "0.6.8"
 handlebars = { version = "3", features = ["dir_source"] }
 lazy_static = "1.4.0"
 serde = "1.0"

Cargo.toml

@@ -1,9 +1,7 @@
-use std::error::Error;
-
 #[path = "lib.rs"]
 mod lib;
 
-pub fn main() -> Result<(), Box<dyn Error>> {
+pub fn main() -> eyre::Result<()> {
     lib::main()?;
 
     println!("blog has been generated; you can now serve its content by running\n\

src/blog.rs

@@ -1,6 +1,5 @@
 use super::posts::Post;
 use serde_derive::{Deserialize, Serialize};
-use std::error::Error;
 use std::path::{Path, PathBuf};
 
 static MANIFEST_FILE: &str = "blog.yml";
@@ -46,7 +45,7 @@ pub(crate) struct Blog {
 }
 
 impl Blog {
-    fn load(prefix: PathBuf, dir: &Path) -> Result<Self, Box<dyn Error>> {
+    fn load(prefix: PathBuf, dir: &Path) -> eyre::Result<Self> {
         let manifest_content = std::fs::read_to_string(dir.join(MANIFEST_FILE))?;
         let manifest: Manifest = serde_yaml::from_str(&manifest_content)?;
 
@@ -122,7 +121,7 @@ impl Blog {
 
 /// Recursively load blogs in a directory. A blog is a directory with a `blog.yml`
 /// file inside it.
-pub(crate) fn load(base: &Path) -> Result<Vec<Blog>, Box<dyn Error>> {
+pub(crate) fn load(base: &Path) -> eyre::Result<Vec<Blog>> {
     let mut blogs = Vec::new();
     load_recursive(base, base, &mut blogs)?;
     Ok(blogs)
@@ -132,7 +131,7 @@ fn load_recursive(
     base: &Path,
     current: &Path,
     blogs: &mut Vec<Blog>,
-) -> Result<(), Box<dyn Error>> {
+) -> eyre::Result<()> {
     for entry in std::fs::read_dir(current)? {
         let path = entry?.path();
         let file_type = path.metadata()?.file_type();

src/blogs.rs

@@ -9,7 +9,6 @@ use sass_rs::{compile_file, Options};
 use serde_derive::Serialize;
 use serde_json::json;
 use std::convert::AsRef;
-use std::error::Error;
 use std::fs::{self, File};
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
@@ -51,7 +50,7 @@ impl<'a> Generator<'a> {
     fn new(
         out_directory: impl AsRef<Path>,
         posts_directory: impl AsRef<Path>,
-    ) -> Result<Self, Box<dyn Error>> {
+    ) -> eyre::Result<Self> {
         let mut handlebars = Handlebars::new();
         handlebars.set_strict_mode(true);
         handlebars.register_templates_directory(".hbs", "templates")?;
@@ -80,7 +79,7 @@ impl<'a> Generator<'a> {
         .replace(std::path::MAIN_SEPARATOR, "/")
     }
 
-    fn render(&self) -> Result<(), Box<dyn Error>> {
+    fn render(&self) -> eyre::Result<()> {
         // make sure our output directory exists
         fs::create_dir_all(&self.out_directory)?;
 
@@ -116,7 +115,7 @@ impl<'a> Generator<'a> {
         fs::write("./static/styles/vendor.css", &concatted).expect("couldn't write vendor css");
     }
 
-    fn render_blog(&self, blog: &Blog) -> Result<(), Box<dyn Error>> {
+    fn render_blog(&self, blog: &Blog) -> eyre::Result<()> {
         std::fs::create_dir_all(self.out_directory.join(blog.prefix()))?;
 
         let path = self.render_index(blog)?;
@@ -136,7 +135,7 @@ impl<'a> Generator<'a> {
         Ok(())
     }
 
-    fn render_index(&self, blog: &Blog) -> Result<PathBuf, Box<dyn Error>> {
+    fn render_index(&self, blog: &Blog) -> eyre::Result<PathBuf> {
         let other_blogs: Vec<_> = self
             .blogs
             .iter()
@@ -161,7 +160,7 @@ impl<'a> Generator<'a> {
         Ok(path)
     }
 
-    fn render_post(&self, blog: &Blog, post: &Post) -> Result<PathBuf, Box<dyn Error>> {
+    fn render_post(&self, blog: &Blog, post: &Post) -> eyre::Result<PathBuf> {
         let path = blog
             .prefix()
             .join(format!("{:04}", &post.year))
@@ -186,7 +185,7 @@ impl<'a> Generator<'a> {
         Ok(path)
     }
 
-    fn render_feed(&self, blog: &Blog) -> Result<(), Box<dyn Error>> {
+    fn render_feed(&self, blog: &Blog) -> eyre::Result<()> {
         let posts: Vec<_> = blog.posts().iter().take(10).collect();
         let data = json!({
             "blog": blog,
@@ -198,7 +197,7 @@ impl<'a> Generator<'a> {
         Ok(())
     }
 
-    fn render_releases_feed(&self, blog: &Blog) -> Result<(), Box<dyn Error>> {
+    fn render_releases_feed(&self, blog: &Blog) -> eyre::Result<()> {
         let posts = blog.posts().iter().cloned().collect::<Vec<_>>();
         let is_released: Vec<&Post> = posts.iter().filter(|post| post.release).collect();
         let releases: Vec<ReleasePost> = is_released
@@ -223,7 +222,7 @@ impl<'a> Generator<'a> {
         Ok(())
     }
 
-    fn copy_static_files(&self) -> Result<(), Box<dyn Error>> {
+    fn copy_static_files(&self) -> eyre::Result<()> {
         copy_dir("static/fonts", &self.out_directory)?;
         copy_dir("static/images", &self.out_directory)?;
         copy_dir("static/styles", &self.out_directory)?;
@@ -236,7 +235,7 @@ impl<'a> Generator<'a> {
         name: impl AsRef<Path>,
         template: &str,
         data: serde_json::Value,
-    ) -> Result<(), Box<dyn Error>> {
+    ) -> eyre::Result<()> {
         let out_file = self.out_directory.join(name.as_ref());
         let file = File::create(out_file)?;
         self.handlebars.render_to_write(template, &data, file)?;
@@ -264,7 +263,7 @@ fn copy_dir(source: impl AsRef<Path>, dest: impl AsRef<Path>) -> Result<(), io::
     copy_inner(source, &dest)
 }
 
-pub fn main() -> Result<(), Box<dyn Error>> {
+pub fn main() -> eyre::Result<()> {
     let blog = Generator::new("site", "posts")?;
 
     blog.render()?;

src/lib.rs

@@ -2,8 +2,8 @@ use super::blogs::Manifest;
 use comrak::{ComrakExtensionOptions, ComrakOptions, ComrakRenderOptions};
 use regex::Regex;
 use serde_derive::{Deserialize, Serialize};
-use std::error::Error;
 use std::path::{Path, PathBuf};
+use eyre::eyre;
 
 #[derive(Debug, PartialEq, Deserialize)]
 struct YamlHeader {
@@ -36,7 +36,7 @@ pub(crate) struct Post {
 }
 
 impl Post {
-    pub(crate) fn open(path: &Path, manifest: &Manifest) -> Result<Self, Box<dyn Error>> {
+    pub(crate) fn open(path: &Path, manifest: &Manifest) -> eyre::Result<Self> {
         // yeah this might blow up, but it won't
         let filename = path.file_name().unwrap().to_str().unwrap();
 
@@ -52,7 +52,7 @@ impl Post {
         let contents = std::fs::read_to_string(path)?;
         if contents.len() < 5 {
             return Err(
-                format!("{path:?} is empty, or too short to have valid front matter").into(),
+                eyre!("{path:?} is empty, or too short to have valid front matter")
             );
         }