C Development with GNU Emacs

Emacs is designed with programming in mind, it supports languages like C, Python, and Lisp natively, offering advanced features such as syntax highlighting, customizable coding styles, and real-time error detection. Its built-in Lisp interpreter makes Emacs highly adaptable, allowing users to shape the editor to fit specific workflows or create entirely new functionalities.

Its rich ecosystem of extensions ensures it remains relevant across diverse fields, from academic writing to system programming, while its customizable interface enables users to optimize their environment for maximum productivity.

It continues to be a reliable choice for those who value control and versatility, proving that a tool designed decades ago can still meet the demands of today’s fast-evolving tech landscape.

Why Choose Emacs?

Emacs is more than just a text editor—it's a powerful, extensible platform for programming, writing, and customization. Unlike modern editors like VS Code or IntelliJ IDEA, Emacs thrives on flexibility and programmability. It allows users to deeply tailor their workflow, turning it into an environment suited for their exact needs. Whether you are coding in C, managing large projects, or even writing novels, Emacs can adapt to your requirements.

For new users, this might seem overwhelming, but once you understand its principles, Emacs becomes a tool that grows with you. This guide aims to help you set up a streamlined Emacs environment, from basic configurations to advanced integrations, ensuring you're productive every step of the way.

Table of Contents

• Creating init.el
• Ensuring the init.el Directory is Correct
• Basic Configuration for Emacs
• Adding the Linux Kernel Coding Style Patterns
• Installing and Configuring the MELPA Package Manager
• Installing the Clang LSP Server
• Enhancing C Development with Company, Projectile, Treemacs, and Magit
• Adding GNU Global, GTags, and Helm-Gtags
• Using YASnippet for Code Templates
• Configuring Semantic for Context-Aware Navigation
• Practical Workflow Example for Development
• Cheat Sheets
• References for Plugins
• Additional Learning Resources

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Steps:

Creating init.el

1. Open Emacs on your system.
2. Use the command C-x C-f (press Ctrl and x, then Ctrl and f), which opens a file for editing.
3. Type the file path ~/.emacs.d/init.el to create or edit your Emacs configuration file and press Enter.
4. Add your desired configurations to the buffer. Once done, save the changes with C-x C-s (press Ctrl and x, then Ctrl and s).

Ensuring the init.el Directory is Correct

To ensure that the Emacs configuration always references the correct directory for the init.el file, add the following snippet to the top of your init.el file:

(setq user-emacs-directory "~/.emacs.d/")

This explicitly sets the user-emacs-directory variable to ~/.emacs.d/, ensuring that Emacs uses the specified path for its initialization file and related configurations. This approach avoids potential issues where Emacs might reference a different directory due to environment-specific settings.

Basic Configuration for Emacs

Here’s a simple and practical Emacs setup, explained clearly to help you understand its purpose. This configuration enhances usability, simplifies the interface, and ensures an efficient coding experience.

This line consolidates all backup files into a single directory (~/.saves). It keeps your projects clean and avoids cluttering your workspace.

(setq backup-directory-alist `(("." . "~/.saves")))

To reduce distractions, this removes unnecessary interface elements like the toolbar, scroll bar, tooltips, and menu bar. A cleaner interface helps you focus on coding without visual noise.

(tool-bar-mode -1)
(scroll-bar-mode -1)
(tooltip-mode -1)
(menu-bar-mode -1)

This setup disables the Emacs startup screen, removes the default message in the *scratch* buffer, and silences the system bell. It creates a distraction-free environment right from the start.

(setq inhibit-startup-screen t
      initial-scratch-message nil
      ring-bell-function 'ignore)

The cursor is set to a box style for better visibility, and the blinking effect is disabled. Automatic pairing of parentheses and indentation are enabled, making coding smoother and faster.

(setq cursor-type 'box
      blink-cursor-mode nil
      electric-pair-mode 1
      electric-indent-mode 1)

Line numbers are displayed globally for easier navigation, and the column number is shown in the status bar to keep track of cursor position in each line.

(global-display-line-numbers-mode t)
(column-number-mode t)

This configuration adds a clean and concise time display in the mode line, showing the day, date, and time in 24-hour format. The load average is excluded to keep the interface minimal.

(setq display-time-format "%a %b %d %R"
      display-time-interval 60
      display-time-default-load-average nil)
(display-time-mode 1)

Selections automatically replace highlighted text when typing, and clipboard integration ensures seamless copying and pasting between Emacs and other applications.

(setq select-enable-primary nil
      select-enable-clipboard t)
(delete-selection-mode 1)

All encoding is set to UTF-8, ensuring compatibility with modern text formats and avoiding encoding issues, particularly when working with international text or source code.

(set-terminal-coding-system 'utf-8)
(set-language-environment 'utf-8)
(set-keyboard-coding-system 'utf-8)
(prefer-coding-system 'utf-8)
(setq locale-coding-system 'utf-8)
(set-default-coding-systems 'utf-8)

Syntax highlighting is enabled globally with global-font-lock-mode. Long lines are wrapped naturally with visual-line-mode. Parentheses are highlighted when the cursor is near them, and recently opened files are tracked for quick access.

(global-font-lock-mode t)
(global-visual-line-mode 1)
(show-paren-mode 1)
(recentf-mode 1)

The tangotango theme provides a visually appealing color scheme. The font is set to "Consolas" with bold weight and size 15.2pt for better readability during long coding sessions.

(use-package tangotango-theme
  :ensure t
  :init (load-theme 'tangotango t))
(set-face-attribute 'default nil :family "Consolas" :height 152 :weight 'bold)

Note: Remember, we are using Emacs Lisp (Elisp), a functional programming language, to configure Emacs. This is a huge advantage, as it allows for highly flexible, programmable customization. The ability to write logic in a powerful Lisp dialect makes Emacs not just an editor, but a platform for personalized workflows.

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Adding the Linux Kernel Coding Style Patterns

The configuration provided below sets up Emacs to strictly adhere to the Linux kernel coding style, emphasizing 8-character tabs, K&R brace placement, and clear readability. It includes a custom alignment function for argument lists, automatic detection of kernel-related files (e.g., files with Kbuild, Kconfig, or kernel headers), and applies the appropriate style automatically. This ensures consistency and simplifies kernel code editing in Emacs.

The linux-kernel-coding-style/setup function configures Emacs for kernel-specific settings like indent-tabs-mode, tab-width and c-basic-offset to 8, while the linux-kernel-coding-style/c-lineup-arglist-tabs-only function aligns argument lists using tabs, maintaining compliance with kernel guidelines. These hooks automatically apply the style to c-mode when editing Linux kernel files, improving productivity and adherence to coding standards.

(eval-when-compile (require 'cl))
(require 'cc)

(defun linux-kernel-coding-style/c-lineup-arglist-tabs-only (ignored)
  "Line up argument lists by tabs, not spaces"
  (let* ((anchor (c-langelem-pos c-syntactic-element))
         (column (c-langelem-2nd-pos c-syntactic-element))
         (offset (- (1+ column) anchor))
         (steps (floor offset c-basic-offset)))
    (* (max steps 1)
       c-basic-offset)))

;; Add Linux kernel style
(add-hook 'c-mode-common-hook
          (lambda ()
            (c-add-style "linux-kernel"
                         '("linux" (c-offsets-alist
                                    (arglist-cont-nonempty
                                     c-lineup-gcc-asm-reg
                                     linux-kernel-coding-style/c-lineup-arglist-tabs-only))))))

(defun linux-kernel-coding-style/setup ()
  (let ((filename (buffer-file-name)))
    ;; Enable kernel mode for the appropriate files
    (when (and filename
               (or (locate-dominating-file filename "Kbuild")
                   (locate-dominating-file filename "Kconfig")
                   (save-excursion (goto-char 0)
                                   (search-forward-regexp "^#include <linux/\\(module\\|kernel\\)\\.h>$" nil t))))
      (setq indent-tabs-mode t)
      (setq tab-width 8)
      (setq c-basic-offset 8)
      (c-set-style "linux-kernel")
      (message "Setting up indentation for the Linux kernel"))))

(add-hook 'c-mode-hook 'linux-kernel-coding-style/setup)

(provide 'linux-kernel-coding-style)

Add this configuration to your Emacs initialization file (init.el). Emacs will now automatically detect Linux kernel files and apply the proper coding style, saving you time and ensuring compliance with the kernel's coding standards.

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Installing and Configuring the MELPA Package Manager

MELPA makes it easy to install additional packages in Emacs.

Steps:

• Add MELPA to Emacs:

  ;; Set up package repositories
  (require 'package)
  (setq package-archives
        '(("melpa" . "https://melpa.org/packages/")
          ("gnu" . "https://elpa.gnu.org/packages/")))
  (package-initialize)

  ;; Refresh package list if needed
  (unless package-archive-contents
    (package-refresh-contents))

• Automatically install packages if they're not present:

  ;; Helper function to install packages
  (defun ensure-package-installed (&rest packages)
    "Ensure that the given PACKAGES are installed."
    (mapcar
     (lambda (package)
       (unless (package-installed-p package)
         (package-install package)))
     packages))

After making changes to your init.el file or adding new configurations, you can refresh Emacs without closing and reopening:

1. Reload the init.el File:

   • Press M-x (Alt + x), type eval-buffer, and press Enter while in your init.el buffer.
   • Alternatively, use the shortcut C-x C-e at the end of the code block to evaluate it.

2. Manually Evaluate Code:

   • Select the code snippet you want to reload, press M-x, type eval-region, and press Enter.

This allows you to immediately apply changes to your Emacs configuration without restart

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Installing the Clang LSP Server

The Language Server Protocol (LSP) provides advanced features like auto-completion and real-time error checking.

Necessary Requirements

Windows

• LLVM/Clang:
  • Download the LLVM installer from the official website: LLVM Releases
  • During installation, make sure to add LLVM to the system PATH.

Linux

• Debian/Ubuntu:

  sudo apt-get install clang clangd

• Fedora:

  sudo dnf install clang clang-tools-extra

FreeBSD

• Install clangd:

  pkg install clangd

Steps:

• Install lsp-mode and company-mode:

  ;; Ensure that the packages are installed
  (ensure-package-installed 'lsp-mode 'company)

  ;; Enable lsp-mode for C/C++
  (add-hook 'c-mode-hook #'lsp)
  (add-hook 'c++-mode-hook #'lsp)

  ;; Enable company-mode for auto-completion
  (add-hook 'after-init-hook 'global-company-mode)

• Configure the path to clangd if necessary:

  ;; Set the path to clangd
  (setq lsp-clients-clangd-executable "clangd")

• Optional: Set up advanced syntax highlighting with lsp-ui:

  ;; Install lsp-ui
  (ensure-package-installed 'lsp-ui)

  ;; Enable lsp-ui
  (add-hook 'lsp-mode-hook 'lsp-ui-mode)

What is LSP and Why Use It?

The Language Server Protocol (LSP) bridges the gap between editors and programming languages, providing features like auto-completion, error checking, and code navigation. This is particularly useful for C/C++ development, where managing headers, debugging, and navigating large codebases can be challenging.

By setting up LSP in Emacs, you gain the ability to:

• View real-time syntax errors as you type.
• Jump to function or variable definitions instantly.
• Access intelligent suggestions for completing code.

This makes Emacs competitive with modern IDEs while retaining its lightweight and customizable nature.

Company, Projectile, Treemacs, and Magit

Enhancing your Emacs setup for C development involves integrating Company, Projectile, Treemacs, and Magit. Company provides auto-completion for C programming, enabling real-time suggestions for functions, variables, and keywords, making coding faster and more efficient. By configuring it to use company-clang, you ensure robust support tailored to C development.

Projectile streamlines project management by allowing quick navigation, file discovery, and project compilation. It pairs seamlessly with Treemacs, which provides a visual, tree-based representation of your project structure, helping you locate and manage files intuitively. Finally, Magit is an advanced interface for Git, providing powerful tools for version control directly within Emacs.

With shortcuts like C-x g, you can perform operations such as commits, branching, and merging interactively, enhancing your workflow and productivity. Here’s the complete configuration to set up these tools in your Emacs environment:

;; Ensure required packages are installed
(ensure-package-installed 'company 'projectile 'treemacs 'treemacs-projectile 'magit)

;; Company Setup for Auto-Completion
(add-hook 'after-init-hook 'global-company-mode) ;; Enable globally
(add-hook 'c-mode-hook
          (lambda ()
            (setq-local company-backends '(company-clang company-capf company-files)))) ;; Configure for C
(setq company-minimum-prefix-length 1
      company-idle-delay 0.2) ;; Show suggestions after 0.2 seconds

;; Projectile Setup for Project Management
(projectile-mode +1) ;; Enable globally
(setq projectile-project-search-path '("~/projects/")) ;; Set your project directory
(setq projectile-completion-system 'default) ;; Use default completion system
(global-set-key (kbd "C-c p") 'projectile-command-map) ;; Set a keybinding for Projectile commands

;; Treemacs Setup for Tree-Based File Navigation
(global-set-key (kbd "M-0") 'treemacs) ;; Toggle Treemacs
(global-set-key (kbd "C-x t t") 'treemacs) ;; Alternate keybinding
(with-eval-after-load 'treemacs
  (treemacs-projectile)) ;; Integrate with Projectile
(setq treemacs-width 30 ;; Set tree width
      treemacs-is-never-other-window t) ;; Prevent Treemacs from taking focus

;; Magit Setup for Git Version Control
(global-set-key (kbd "C-x g") 'magit-status) ;; Open Magit status interface

Practical Workflow Example

Let’s see how you can combine these tools in a real-world scenario:

1. Open a Project:
   • Use C-c p f to quickly find a file within your project directory using Projectile.
2. Navigate Files Visually:
   • Open Treemacs with M-0, and use the arrow keys to browse your project structure. Double-click a file to open it.
3. Git Workflow with Magit:
   • Stage changes: Open Magit with C-x g, press s to stage files.
   • Commit: Press c c to commit changes with a message.
   • Push: Use P to push changes to your remote repository.
4. Code Completion:
   • While editing a .c file, type a function name partially and use company-mode suggestions by pressing TAB.

Enhancements to Add to the Article

1. GNU Global and GTags Configuration:
   • Add instructions for setting up GNU Global and GTags for code navigation:

   ;; Install and configure ggtags
   (require 'ggtags)
   (add-hook 'c-mode-common-hook
             (lambda ()
               (when (derived-mode-p 'c-mode 'c++-mode 'java-mode 'asm-mode)
                 (ggtags-mode 1))))

   ;; Keybindings for ggtags
   (define-key ggtags-mode-map (kbd "C-c g s") 'ggtags-find-other-symbol)
   (define-key ggtags-mode-map (kbd "C-c g h") 'ggtags-view-tag-history)
   (define-key ggtags-mode-map (kbd "C-c g r") 'ggtags-find-reference)
   (define-key ggtags-mode-map (kbd "C-c g f") 'ggtags-find-file)
   (define-key ggtags-mode-map (kbd "C-c g u") 'ggtags-update-tags)

1. Helm-Gtags Integration:
   • Include configuration for helm-gtags to enhance project navigation:

   (setq
    helm-gtags-ignore-case t
    helm-gtags-auto-update t
    helm-gtags-use-input-at-cursor t
    helm-gtags-pulse-at-cursor t
    helm-gtags-prefix-key "\C-cg"
    helm-gtags-suggested-key-mapping t)

   (require 'helm-gtags)
   (add-hook 'c-mode-hook 'helm-gtags-mode)
   (add-hook 'c++-mode-hook 'helm-gtags-mode)

1. Yasnippet Templates:
   • Include YASnippet for code templates:

   (require 'yasnippet)
   (yas-global-mode 1)
   ;; Example snippet for C-mode
   (add-to-list 'yas-snippet-dirs "~/.emacs.d/snippets")
   (yas-reload-all)
   (add-hook 'c-mode-hook #'yas-minor-mode)

1. Semantic Configuration:
   • Add Semantic for context-aware code completion and parsing:

   (require 'cc-mode)
   (require 'semantic)
   (global-semanticdb-minor-mode 1)
   (global-semantic-idle-scheduler-mode 1)
   (semantic-mode 1)

   ;; Add include paths for Semantic
   (semantic-add-system-include "/usr/include/boost" 'c++-mode)
   (semantic-add-system-include "~/linux/include")

1. Additional Code Navigation Features:
   • Mention semantic-symref for reference gathering:

   (add-hook 'c-mode-common-hook
             (lambda ()
               (local-set-key (kbd "C-c , g") 'semantic-symref)))

These additions enhance the existing content by providing support for advanced navigation, project management, and automation tools in Emacs, aligning the article with best practices for modern C/C++ development.

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Cheat Sheets

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References for Plugins

• lsp-mode: Language Server Protocol support for auto-completion and error checking. GitHub
• company-mode: Context-aware autocompletion. GitHub
• lsp-ui: UI enhancements for lsp-mode. GitHub
• projectile: Project navigation and management. GitHub
• treemacs: Tree-based file explorer. GitHub
• magit: Git interface for Emacs. GitHub
• ggtags: GNU Global integration for code navigation. GitHub
• helm-gtags: Navigation with GNU Global and Helm. GitHub
• yasnippet: Snippet management for reusable code. GitHub
• semantic: Advanced code parsing and navigation. GNU CEDET

Additional Learning Resources

• Emacs for Beginners: A beginner-friendly guide to setting up and using Emacs. Link
• Introduction to Emacs Lisp: Learn how to customize Emacs using Lisp. Link
• Linux Kernel Coding Style: Official documentation on kernel coding standards. Link
• Setting Up Emacs for C Development: A practical guide to configure Emacs for C/C++ programming. Link