Write Powerful Rust Macros

Overview

This is the code for Manning's Write Powerful Rust Macros book.

The code is organized by chapter. Exercise solutions are not located in a separate appendix directory, instead they sit next to the example code for the chapter they appeared in, and always end in -exercise. Every project besides the exercise solutions represents either a complete example, or (since many chapters are based around a single example) show stages in the development of that example. Each one contains a README file that gives some idea what part of the chapter it is related to.

Util

The util directory contains a script, create_setup.sh that allows you to generate procedural macro setups like the ones used in this book, with either 1, 2, or 3 subdirectories. All three options are explored in the book.

Usage:

./create_setup.sh name 2

Errata

Thanks again to the readers who reported these.

Section 1.2 (page 4)

C++, not C, has templates

Section 1.3.2 (page 7)

#[derive(Clone)} should be #[derive(Clone)]

Section 2.1.4 (page 15)

Nonemtpy in the title should be nonempty

Section 2.1.4 (page 18)

$[($x:expr),+] => (: should not end with :

Section 2.4 (page 39)

trailing comments should be trailing commas

Section 5.1 (page 82, 84, and 87)

In this chapter quote::__private::TokenStream should be proc_macro2::TokenStream.

Section 5.1 (page 84)

For the 'ugly return type' a reference to what is currently pages 264–265 would be useful.

Now focus on the code inside map. would be clearer with a reference to the listing: Now focus on the code inside map in listing 5.4.

For clarity, replace So we need an identifier. with the following: The simplest way to solve the issue is to use TokenStream::from_str. This method will try to turn your string into a TokenStream that we can use as an identifier. The other approach is to construct an identifier ourselves.

Section 6.4.3 (page 114)

Minor: pub function could be pub(crate).

Section 6.4.5 (page 120)

assert_eq!(gleipnir.other_necessities.len(), 3) should preferably be assert_eq!(gleipnir.other_necessities.len(), 3);

Section 7.5 (page 138)

use quote::{ToTokens}; should be use quote::ToTokens;

Section 7.7 (page 143)

ast.to_token_stream() should be ast.to_token_stream().into(). The into() seems to have disappeared in the proofs, it was present in the code.

Section 7.9.2(e.g. p. 155)

proc_macro_error uses syn version 1. There's a proc-macro-error-2 (fork of the original project) that uses syn version 2.

Section 8.1 (page 164)

The tests are added to main.rs of builder-usage (not really a bug, but it's unclear where the given tests should be placed).

Section 10.1.2 (page 237)

The Ok and ? are redundant. So this:

Ok(serde_yaml::from_reader(file)
        .map_err(|e| {
            syn::Error::new(Span::call_site(), e.to_string())
        })?)

Can be changed to

serde_yaml::from_reader(file)
        .map_err(|e| {
            syn::Error::new(Span::call_site(), e.to_string())
        })

Section 10.7 (page 258)

Besides SO and Reddit, the official Rust forums should also be mentioned.

Appendix (page 260)

trailing comments should be trailing commas