One Editor To Rule Them All

1
One Editor To Rule Them All

• Dan Berger dberger_at_cs.ucr.edu
• Titus Winters titus_at_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

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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
  were talking about here) and XEmacs (the one
  were not).
• If you want to know more try WikiPedia/wiki/Emacs

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Fundamental Emacs Ideas

• Emacs is essentially a lisp interpreter.
• No this isnt an elisp hacking seminar.
• Whats 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)

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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

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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
  youre editing C/C code vs. Python code.

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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

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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

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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

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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.

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Emacs as an IDE

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

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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.

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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 its not in that directory.

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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

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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

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Nifty Features

• font-lock-mode
• flyspell-mode
• M-x ispell-comments-and-strings
• ediff mode
• tramp

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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

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Flyspell-Mode

• On-the-FLY spell checking.
• Turn it on with M-x flyspell-mode
• As you move across text, it gets 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-)

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M-x ispell-comments

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

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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

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tramp

• A tool for opening files that are not local over
  SSH
• Any file (anywhere) can be represented as
  /user_at_hostpath/to/file
• i.e. /titus_at_hill.html/techsem.html
• Very low bandwidth so its usable over
  slow/unreliable links.
• Not in the standard Emacs package, but should be
  installed on CS machines soon.

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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/

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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 lets 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.

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Emacs on MS Windows

• http//www.gnu.org/software/emacs/windows/
• The windows portions of Dans .emacs file are old
  and not supported.
• I havent used Windows in years so Ive no idea
  if that config is still needed or functional.

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Stuff We Didnt Cover

• Emacs can be a mail reader, web browser,
  psychologist, and much, much more.
• We didnt cover elisp the lisp dialect that
  emacs uses theres a good tutorial on-line
• http//www.gnu.org/software/emacs/emacs-lisp-intro
  /