One Editor To Rule Them All

1. One Editor To Rule Them All Dan Berger dberger@cs.ucr.edu Titus Winters titus@cs.ucr.edu

2. Introduction • The hacker community has a tradition of treating their favorite text editor with a reverence bordering on religious fanaticism… Editor wars are usually fought between the devottees of Emacs and vi, the most popular editors on Unix. - http://wikipedia.org/wiki/Editor_wars

3. Outline • A Brief Emacs history • Fundamental Emacs Concepts • Basic Commands/Key Chords • Using Emacs as an IDE • “Nifty” Features • Customizing Emacs

4. Emacs: A Brief History • Originally written in 1976 by Richard Stallman (scary dude) as a set of Editor MACroS for the TECO editor. • Two common strains in the wild: Emacs (the one we’re talking about here) and XEmacs (the one we’re not). • If you want to know more: try WikiPedia/wiki/Emacs

5. Fundamental Emacs Ideas • Emacs is essentially a lisp interpreter. • No – this isn’t an elisp hacking seminar. • What’s important is that elisp is Turing complete; • That means Emacs is horribly extensible – and can do anything you can express in elisp (see Turing Complete)

6. Terminology • A “key chord” is a set of keys pressed together. • Text is stored in “buffers” – often, but not always, buffers hold the contents of files. • Reading a file into a buffer is called “visiting” the file. • Portions of the emacs display are called “windows” • Multiple emacs displays are each called a “frame”

7. More Emacs Ideas • Emacs does its work by calling elisp functions – which are often bound to key chords. • Buffers have associated major and minor editing modes – so the editor can behave differently when you’re editing C/C++ code vs. Python code.

8. Basic Commands (I) • Starting emacs: • emacs [-nw] [file1 file2 … fileN] • emacs will run either in GUI mode (under X) or tty mode (in a terminal, or with the –nw flag) • Exiting emacs: • C-x C-c • Control-”x” Control-”c” • M-x save-buffers-kill-emacs • Meta (Alt or Esc)-”x” “save-buffers-kill-emacs”

9. Basic Commands (II) • Get help: C-h • Run a tutorial: C-h t • Open (visit) a file: C-x C-f • Save a buffer to a file: C-x C-s

10. Mark and Selection • Manipulating regions of text is easy – once you understand “the mark” • The mark is one end of the region you want to work on – the other end is determined by “the point” – which is the current cursor position. • Set the mark: C-spc

11. Manipulating Regions • Many emacs commands (can) work on a region of text. Remember – a region is between the mark and the cursor (point). • Examples: • C-w will “kill” (cut) the selected region • Esc-w will copy the selected region • C-y “yanks” (pastes) it back • M-x ispell-region will spell check the selected region of text.

12. Emacs as an IDE • Emacs was written by developers for developers – so it’s not surprising that it makes a pretty good IDE. You can: • Write code • Navigate code • Compile code • Debug Code • Interface with revision control (CVS)

13. Writing Code • Emacs has major modes for just about every language you can imagine. • It will perform syntax-aware indentation, can colorize the code, and is generally “aware” of the structure of the code. So you can jump around basic blocks, functions, etc. • Each major mode is different – C-h m will describe the current modes.

14. Navigating Code • Emacs includes a support program called etags – it builds a cross reference (index) of a set of files, and helps emacs find symbols. • Complete use is outside the scope of this talk, but Google can help.

15. Compiling • Simple: M-x compile • By default emacs will run Make – but you can run any command you want. • It will cd into the directory containing the file you were visiting when you invoked the compile. • This means that you may have to tell make which Makefile to use, if it’s not in that directory.

16. Debugging • GUD – Grand Unified Debugger mode – knows how to interface with many “standard” unix debuggers, including gdb (and dbx) • M-x gdb • M-x pdb • M-x jdb • An example is worth a thousand words…

17. CVS Integration • Emacs will recognize if a file (directory) is managed by CVS – and give you a set of CVS commands you can perform without leaving the editor including; • Checkout a file • Commit changes to a file • Diff a file against the repository • Register a new file with revision control

18. Nifty Features • font-lock-mode • flyspell-mode • M-x ispell-comments-and-strings • ediff mode • tramp

19. Font-Lock-Mode • Provides syntax hi-lighting for languages emacs understands (many). • You can customize the colors it uses – and the face (font). • Turn it on with: • M-x font-lock-mode • Colorize your world with: • M-x font-lock-fontify-buffer

20. Flyspell-Mode • On-the-FLY spell checking. • Turn it on with M-x flyspell-mode • As you move across text, it get’s spell checked. Errors are marked. • If you want to spell check the entire buffer, • M-x flyspell-buffer • To see suggested spellings, place the point (cursor) on the misspelled word and middle-click (or press Esc-$)

21. M-x ispell-comments • Just what it sounds like – it will spell-check your code – paying attention to comments and strings (between quotes).

22. ediff mode • diff (the file comparison tool) on steriods. • Give emacs two (or three!) files to compare – and it will help you navigate the differences – making it easy to update one file with the changes in another. • M-x ediff-files • M-x ediff-buffers

23. tramp • A tool for opening files that are not local over SSH • Any file (anywhere) can be represented as /user@host:path/to/file • i.e.: /titus@hill:.html/techsem.html • Very low bandwidth – so it’s usable over slow/unreliable links. • Not in the standard Emacs package, but should be installed on CS machines “soon.”

24. Tramp (cont.) • If you want to install it on a personal machine (Linux or Windows), you can fetch it from: • http://savannah.nongnu.org/projects/tramp/

25. Customizing Emacs • On startup, emacs reads and evaluates ~/.emacs – which can contain arbitrary elisp code you want executed on startup. • My .emacs file (~dberger/.emacs) is world readable – let’s take a quick look at it now… • Recent versions of emacs also include a package to help you customize emacs – M-x customize will get you started.

26. Emacs on MS Windows • http://www.gnu.org/software/emacs/windows/ • The windows portions of Dan’s .emacs file are old – and not “supported.” • I haven’t used Windows in years – so I’ve no idea if that config is still needed or functional.

27. Stuff We Didn’t Cover • Emacs can be a mail reader, web browser, psychologist, and much, much more. • We didn’t cover elisp – the lisp dialect that emacs uses – there’s a good tutorial on-line: • http://www.gnu.org/software/emacs/emacs-lisp-intro/