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DépartementOffice
Emacs, a performant IDE for Perl
Tutorial for YAPC.:EU:::2009, Lisbon
DépartementOffice
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Overview
• Intended audience– Emacs newcomers– [ seasoned Emacs users … may find some additional tips ]– curious …
• Topics– Intro– Emacs concepts– General editing– Perl programming– External tools– Emacs-Perl integration : extension packages
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What is Emacs ?
• "Emacs is the extensible, customizable, self-documenting real-time display editor".
– advanced : provides much more than simple insertion and deletion. It can control subprocesses, indent programs automatically, show two or more files at once, and edit formatted text.
– self-documenting : can type C-h at any time to find out what the options are.
– customizable : thousands of variables – extensible : internal Lisp interpreter– feature-rich : thousands of commands
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Emacs history
• early 1970s : initial work on PDP computers (MIT Labs)
• 1976 : first release• 1981 : Gosling Emacs on Unix• 1986 : GNU Emacs 15.34• 1991 : XEmacs fork (formerly Lucid Emacs)• 2008: GNU Emacs 22.3
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Emacs main concepts
• buffer : basic editing unit (text being edited). Can be bound to various contents like :– file (local/remote)– computed content (listings, compilation results, shell, email, etc.)– external process
• window : screen area for displaying buffer content• frame : OS window• mode : set of options for editing some kind of content
– major mode : mutually exclusive– minor mode : additional options (plugin)
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Other concepts
• region : portion of buffer between mark and point
• rectangle : rectangular area instead of linear text
• register : memory for storing text / position / rectangle
• macro : recorded sequence of keys• desktop : saved Emacs session
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User input
• Input events– character events– modifiers : <CTRL>, <ALT>, <META>, <SUPER>– mouse, scroll, click, focus, etc.
• Key sequence– prefix key keymap. Ex:
• C-x General extended commands• C-h Help commands• C-c Mode-specific extended commands
– complete key command
• Keymap– binding key command– global / local
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Entering commands/args in minibuffer
• Auto-completion• Default argument• Editing (cut/paste/move/etc.)• Command history
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Modes may implement …
• additional commands• local implementation for generic operations
– ex: comment-region, indent-region
• syntax highlighting• local keymaps• local menus• modifications to the display (ex. status line)• hooks
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Editing
• Move– by character, word, sentence, paragraph, page
• Copy / Cut / Paste– kill ring : history of killed fragments
• Search / Replace– incremental / regex– word search (without regard to punctuation)– clever case substitutions– recursive edit
• Abbrevs• Undo
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Files
• File names / completion / disambiguation• Remote files (ange-ftp / tramp)• Archives / compressed files• Mode chosen automatically from name or
content• Bookmarks (filename / position / comment)• Shadowing (automatic replication)• Filesets
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Editing directories
• listing• create / rename / delete• bulk operations (mark / regexp )• open subdirectories in same buffer• chmod, mkdir, etc.• exec shell command on file(s)
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Shell
• Inferior process– filename completion– history ring– editing command-line– directory tracking– remote host (telnet, rlogin, etc)
• Eshell – no process, all done in Emacs
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Help
• Info (manual)• Help on
– variables– functions– keys– bindings– mode– apropos
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Programming modes : generic features
• Recognize top-level definitions– go to begin / end, set region
(C-M-h), imenu
• Indentation– clever syntax parsing; various
indent styles (K&R, BSD, Gnu, etc.)
• Balanced parentheses– begin / end, up / down, kill,
• (C-M-LEFT, C-M-UP, ..)– blink-matching
• Comments– insert, realign, comment /
uncomment region, reformat
• Syntax highlighing
• Restricting editing scope– hideshow minor mode– narrowing
• (C-x n d / w)
• Autocompletion
• Electric characters– automatic reindent / newline
• Tags support
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Cperl mode
• based on C-mode– indenting– electric parentheses– automatic expansion (if, else, while, do, foreach, …)– syntax highlighting– binding to perlinfo– menu, tools– perldb : gud bindings
• next / step• break (C-x SP)
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Compiling and testing
• Compilation– launch compiler subprocess ("perl", "gcc", "make", etc.)– mod-compile.el : additional layer
• adapt compilation command to current language / context
– parse errors and navigate to source files– usual Emacs commands for viewing results / debug logs
• GUD (Grand Unified Debugger)– shell buffer– navigate to source files
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Searching
• builtin support for "grep"• ack.el : adaptation for "ack"• navigate in matched files like for the compilation
buffer
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Autocompletion
• Static sources– Tags– Language-specific doc
• More context-aware– Emacs extensions : Sepia, PerlySense
• Dabbrev– most recent, preceding word for which this is a prefix– if none, search following words– if none, search other "friend" buffers
• Hippie-expand– ring of try functions
• try-complete-file-name• try-expand-all-abbrevs• try-expand-line• try-expand-dabbrev• try-expand-whole-kill
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External filters
• Ex: perltidy
; tidy perl code on region(defun perltidy () "run perltidy on the current region or buffer." (interactive) (shell-command-on-region (point) (mark)
"perltidy -q" nil t))
(global-set-key "\C-ct" 'perltidy)
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Version control
• generic version control (VC)• psvn.el : SVN support
– status • dired-like
– log– ediff
• similar modes for git
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Differences / patches
• ediff-mode– both versions side-by-side (horizontal or vertical)– ediff commands
• previous / next• copy A B / B A
– apply patches (multifiles OK)
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perlcritic
• mode perlcritic.el distributed with Perl::Critic– apply on buffer– apply on region– parse output
• other solution: treat as a standard compile command– must configure .perlcriticrc so that Emacs understands
filenames
verbose = %f:%l:%c: %m, %e (%p, severity %s)\n
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Emacs::EPL
• Perl-Emacs IPC integration, followup to "Perlmacs"• looks like this was very nice work
– adapted environment for running Perl under Emacs• redefine STDIN, STDOUT as hooks to Emacs minibuffer• populate ENV• …
– can write Emacs modules in Perl instead of elisp !
• last distribution dates back to 2001, using Perl 5.004
• couldn't get it to work
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Devel::PerlySense
• Perl process in the background• Lots of features
– links to doc– class hierarchy analysis and method analysis– jump to definition / class– run / debug– run tests– interact with ack– notion of "project"– file templates
• but very CPU-intensive and slow
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Sepia
• last distrib May 09• Inspired by Emacs Lisp dev. philosophy• Features
– completion on partial words, i.e. L:U List::Util– inferior Perl process with REPL loop– analyses opcodes– links to doc, to func definitions, to modules
only recognizes core modules/functions– didn't figure how to let it read perl/site/lib !
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Emacs::PDE
• last distrib July 2008• Features (pde-load)
– projects– smart compile (C-c r) / debug– tags / menus / tree view (C-c C-v TAB)– perldoc integration with browser (C-c C-v RET, C-c C-v C-p)– special indenting mode– integrate with perltidy / perlcritic– interactive perl shell
no install problems• need to learn more
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