@keyboardspam on Rust Emacs dynamic Module bindings · 3 months ago

2h 0m 46s logged

I made the test runner work with cargo test and removed all the old autoconf stuff. This makes things easier for other people to work on the project who don’t know how to use autoconf and only know how to use the rust based tools.

Ship #1 Changes requested

@keyboardspam on Rust Emacs dynamic Module bindings · 3 months ago

What did you make?

I made a fork of the emacs-module-rs crate
because the repository seems to be abandonned, and my prs have been ignored for a
week now and I need changes for my other stardance project.

emacs-module-rs and my fork is a library for Rust that allows writing dynamic modules
for Emacs (which are shared libraries which are loaded by Emacs to
extend the functionality of the text editor, often for performance
reasons).

The reason that I wanted to change the upstream code was that upstream code has
“bloated” code generation where the library would do things like
allocate strings at link-time in order to create the name of the LISP function
which is inefficient since this information can be computed at compile
time, making the extra allocations (which are fallible and may crash
Emacs) unnecessary.
There are other things that I think the upstream code did wrong and rather than wait for the maintainers who haven’t committed anything in 4 months, I decided to fork the project.

After making my other project which is a Emacs dynamic module to using
the binary size of the compiled shared library went down by ~20kb
showing that the crate is unnecessarily bloated.

What was challenging?

What was challenging was rewriting the build system for the
project. While the crate is a typical Rust project, meaning it uses
cargo for compiling, the test harness needs to use the Emacs’ ert library
so it needs some sort of build system to compile the modules and run
the tests.

In upstream, they use a custom cargo subcommand
which contains a lot of dependencies which slowed compilation in CI runs.

This made me want to use a different build system and I settled on
autoconf without automake so that the configure script would gather
information about the system
and configure the build system accordingly.

This was difficult because I had never used autoconf before and I had
to learn this new build system.

What are you proud of?

I am proud of the fact that I was able to refactor and improve the
emacs-module-rs crate into something better.

What should people know so they can test your project?

In order to test the project you would need to install an Emacs
version which is at least version 25 and a recent Rust compiler. For a
basic emacs dynamic module you should read this guide for instructions.

P.S. the demo image is an image of my other project which now uses this new library.

3 devlogs
12h

Try project → See source code →

Open comments for this post

@keyboardspam on Rust Emacs dynamic Module bindings · 3 months ago

2h 40m 22s logged

I updated the documentation to include changes from the new version, and made the documentation code blocks get tested under the rustdoc documentation testing harness.

Open comments for this post

@keyboardspam on Rust Emacs dynamic Module bindings · 3 months ago

1h 50m 24s logged

I changed the build system to one that uses autoconf + autoconf configured makefiles (not automake) so the build system went from a hacky shell around cargo to an extra hacky configure.ac script.

Open comments for this post

@keyboardspam on Rust Emacs dynamic Module bindings · 3 months ago

7h 9m 54s logged

I removed static items from the initialization code. Basically in upstream they want to have good developer experience so they want to have macros that both declare functions and register them into the runtime by running code at dynamic linking time that modifies statics with things like mutexes even though the code will be ran single-threaded at load time. My fork of the project removes those features so that the code is simpler and performant by requiring the user code to register the things they need themself.