String Delimiters: Because Backslash Escaping Is for Amateurs

2026-02-24

Ruby's % notation mirrors Perl's quoting operators almost exactly. Use any delimiter you want to avoid escaping quotes and slashes. If you've ever written /\/var\/log\/\w+\.log/ and felt your soul leave your body, this post is for you.

Part 1: The Perl to Ruby Quoting Map

Perl	Ruby	Interpolation?	Purpose
`q~text~`	`%q~text~`	No	Single-quoted string
`qq~text~`	`%Q~text~`	Yes	Double-quoted string
`qw(a b c)`	`%w~a b c~`	No	Word array
`qx(cmd)`	`%x~cmd~`	Yes	Shell command
`m~pattern~`	`%r~pattern~`	Yes	Regex
N/A	`%i~a b c~`	No	Symbol array
N/A	`%W~a #{b} c~`	Yes	Word array with interpolation
N/A	`%I~a #{b} c~`	Yes	Symbol array with interpolation

Part 2: Delimiter Choices

Any non-alphanumeric character works as a delimiter. Paired brackets auto-match:

# All of these are equivalent:
%Q~Value is: #{value}~
%Q{Value is: #{value}}
%Q[Value is: #{value}]
%Q<Value is: #{value}>
%Q|Value is: #{value}|
%Q!Value is: #{value}!
%Q/Value is: #{value}/

Preferred style: tildes (~~) to match Perl habits. Your fingers already know the way.

Part 3: String Delimiters

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Single-quoted (no interpolation)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sql = %q~SELECT * FROM users WHERE name = 'O'Brien'~
# No need to escape the apostrophes!

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Double-quoted (with interpolation)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
html = %Q~<div id="main" class='container'>#{content}</div>~
# No need to escape quotes of either kind!

Part 4: Word Arrays and Symbol Arrays

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Without interpolation (most common)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
files = %w~config.yml database.yml secrets.yml~
# => ["config.yml", "database.yml", "secrets.yml"]
# Perl: qw(config.yml database.yml secrets.yml)

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# With interpolation
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
prefix = "app"
dirs = %W~#{prefix}/models #{prefix}/views #{prefix}/controllers~
# => ["app/models", "app/views", "app/controllers"]

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Array of symbols (no Perl equivalent)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
methods = %i~start stop restart status~
# => [:start, :stop, :restart, :status]

Part 5: Regex Delimiters

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Regex with %r (like Perl's m~~)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
pattern = %r~https?://[^\s]+~i
url_found = line =~ %r~https?://(\S+)~

# No need to escape slashes in paths:
path_match = line =~ %r~/var/log/\w+\.log~
# Compare to: line =~ /\/var\/log\/\w+\.log/  (ugly!)

Part 6: Shell Commands

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Execute shell command (like Perl's qx~~)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
output = %x~ls -la /tmp~
disk_usage = %x~df -h /~.chomp

# Backticks also work:
output = `ls -la /tmp`

Part 7: Heredocs, Ruby's Secret Weapon

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Squiggly heredoc (strips indentation)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
sql = <<~SQL
  SELECT *
  FROM users
  WHERE status = 'active'
SQL

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# With interpolation
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
msg = <<~MSG
  Found #{count} errors in #{filename}
  Processing took #{elapsed} seconds
MSG

# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
# Single-quoted heredoc (no interpolation)
# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
template = <<~'TEMPLATE'
  Hello #{name}
  This #{won't} interpolate
TEMPLATE
# The #{name} and #{won't} stay as literal text

Perl	Ruby	Notes
`<<END`	`<<END` or `<<~END`	Ruby's `~` strips indentation
`<<'END'`	`<<~'END'`	Single-quoted (no interpolation)
`<<"END"`	`<<~"END"` or `<<~END`	Double-quoted (default)
Indentation preserved	`<<~` strips leading whitespace	Ruby wins here

The squiggly heredoc (<<~) is a genuine Ruby improvement over Perl. It automatically strips the common leading whitespace, so your heredoc content can be indented with your code without the indentation appearing in the output. Once you use it, you'll wonder how you ever lived without it.