Racer for Emacs

This is the official Emacs package for Racer.

Table of Contents

• Racer for Emacs
  • Completion
  • Find Definitions
  • Describe Functions and Types
  • Installation
  • Tests

Completion

racer.el supports code completion of variables, functions and modules.

You can also press F1 to pop up a help buffer for the current completion candidate.

Note that due to a limitation of racer, racer.el cannot offer completion for macros.

Find Definitions

racer.el can jump to definition of functions and types.

You can use M-. to go to the definition, and M-, to go back.

Describe Functions and Types

racer.el can show a help buffer based on the docstring of the thing at point.

Use M-x racer-describe to open the help buffer.

Installation

1. Install Racer:

   $ cargo install racer
   

2. Allow Emacs to install packages from MELPA:

   (require 'package)
   (add-to-list 'package-archives '("melpa" . "https://melpa.org/packages/"))

3. Install racer: M-x package-install RET racer RET

4. Download the rust sourcecode, and configure emacs to find your rust source directory:

   (setq racer-rust-src-path "<path-to-rust-srcdir>/src/")

5. Configure Emacs to activate racer when rust-mode starts:

   (add-hook 'rust-mode-hook #'racer-mode)
   (add-hook 'racer-mode-hook #'eldoc-mode)

   For completions, install company with M-x package-install RET company RET. A sample configuration:

   (add-hook 'racer-mode-hook #'company-mode)
   
   (require 'rust-mode)
   (define-key rust-mode-map (kbd "TAB") #'company-indent-or-complete-common)
   (setq company-tooltip-align-annotations t)

   For automatic completions, customize company-idle-delay and company-minimum-prefix-length.

6. Open a rust file and try typing use std::io::B and press TAB.

7. Place your cursor over a symbol and hit M-. to jump to the definition.

8. Hit M-, to jump back to the symbol usage location.

Tests

racer.el includes tests. To run them, you need to install Cask, then:

$ cask install
$ cask exec ert-runner