Outline

• Short demo
• Tools to create tag files
• Exuberant Ctags
• ctags command line
• Kinds of Perl tags
• Very small example
• What is inside tag files?
• Basic Vim commands
• Fully qualified tags
• Tags for non-Perl source
• Using multiple tag files
• Write your own tag-producing code
• Contribute to development

Short Demo

Tools to create tag files

• Exuberant Ctags
  • Supports multiple languages
  • Written in C
  • Fast, basic, gets job done
  • I am the maintainer of the Perl part
• Perl::Tags
  • Perl source only
  • Written in Perl
  • Supports more objects (Moose, anyone?)
  • Interesting features; extensible; may be slow
  • I contributed some tidbits to it

Exuberant Ctags

Supports Many Languages

Ant Asm Asp Awk Basic BETA C C++ C# Cobol DosBatch Eiffel Erlang Flex Fortran Go HTML Java JavaScript Lisp Lua Make MatLab ObjectiveC OCaml Pascal Perl PHP Python REXX Ruby Scheme Sh SLang SML SQL Tcl Tex Vera Verilog VHDL Vim YACC

ctags command line

• Extensive set of command-line options
• Which files to index
• Specifying output
• Perl-related options
• And more
• ...and more

Which files to index

# Index one file:
ctags my-file.pm

# Index recursively:
ctags -R dir dir dir

# Index everything in @INC:
ctags -R `perl -e 'print "@INC"'`

# A bunch of files:
ctags -L list-of-files.txt

Specifying output

• By default, tags is created
• Use -f option to override
• -f- prints to stdout
• Use -a to append to existing tags file
• Use -e for emacs (TAGS is created)

Kinds of Perl tags

Ask ctags --list-kinds=Perl

• constants
• formats
• labels
• packages
• subroutines
• subroutine declarations (off by default)

Very small example

package My::Package;
use constant ABC => 123;
sub do_this;
do_this @ARGV;
sub do_this {
    AGAIN: write; shift;
    goto AGAIN if @_;
}
format =
@#####
$_[0]
.

What is inside a tag file?

• header
• one tag per line
• tags are sorted by default
• Vim defaults to binary search

Basic Vim commands

Jump to tag:

• I'm feeling lucky: :tag or Ctrl + ]
• :tselect or g + ]
• :tjump or g + Ctrl + ]

Jump back:

• Ctrl + t

See where you've been:

• :tags

Fully qualified tags: why

Use case 1

# For calls like this:
File::Temp::unlink0($fh, $local);

Use case 2

vi -t Edit::This::function

Fully qualified tags: how

extra option to ctags

ctags --extra=+q

I like them: ~/.ctags

--extra=+q

Setting up Vim

:au FileType perl setlocal iskeyword+=:

Tags for non-Perl source

Seen in Perl code:

• C
• JavaScript
• SQL
• More

Using multiple tag files

• In Vim: :set tags=tags1,tags2
• Merging tag files
  • For default files, header is optional
  • Merging as easy as

LC_ALL=C sort tags1 tags2 > tags

or

perl -e 'print sort <>' tags1 tags2 > tags

Write your own tag-producing code

• Easier than one might think
• Just generate some ex commands
• Example: .ini files used by AppConfig

Contribute to development

• https://github.com/fishman/ctags
• https://github.com/osfameron/perl-tags