ruby-overview.md

Ruby Overview

• Ruby Core
• Ruby Standard Library

IRB and Signals

• CTRL-C sends INT ("interrupt") signal. Ignores input and creates a new prompt.
• CTRL-D sends EOT ("end of transmission") signal. Exits.
• CTRL-Z sends TSTP ("terminal stop") signal. Nothing.
• CTRL-\ sends QUIT signal. Unknown. (Note: does not dump core like other processes.)
• exit

Kernel

• Kernel

Math

• Math
• CMath

IO

• IO
• File
• Dir
• FileTest
• FileUtils
• Find
• Pathname
• Tempfile
• StringIO

Strings

• Regexp
• StringScanner
• Scanf

Date/Time

• Date
• DateTime
• Time
• time.strftime()

Net

• URI
• Net::HTTP
• OpenURI
• CGI

Shell / Command Line

• OptParse
• Open3
• system()
• `cmd`
• Shell
• ARGV
• ARGF
• STDIN and $stdin
• STDERR and $stderr
• STDOUT and $stdout
• exit

---

Magic Variables

The $_ variable.

ruby -e 'puts $_ while STDIN.gets'
ruby -e 'STDIN.each_line { |l| puts l.upcase }'
ruby -ne 'puts $_.upcase'
ruby -pe '$_.upcase!'

Arrays

• slice()
• take()
• drop()

Enumeration, Streams, and Maps

• lazy(), Lazy
• map()
• reduce()
• flat_map()
• select()
• grep()

Security

• SecureRandom
• OpenSSL

Objects

• Binding
• Proc
• lambda()
• method()
• clone()
• freeze()
• inspect()

Introspection

• ObjectSpace
• Tracer
• pp
• require "debug"

Profiling

• Profile
• Benchmark

Process

• Process
  • Process.pid
• Thread
• Mutex
• Signal
• ENV

File Formats

• DATA
• ERB
• CSV
• Marshal
• PStore
• Zlib
• Logger

Safe Navigation Operator

• &. (Ruby 2.3.0 Release Notes)

# rails
obj.try!(:foo)

# ruby 2.3.0
obj&.foo

Array#dig and Hash#dig

numbers = [2, [3, [6]]]
six = numbers.fetch(1).fetch(1).fetch(0)
six = numbers.dig(1, 1, 0)

person = {
  name: {
    first_name: "A",
    last_name: "Z"
  }
}

first_name = person.fetch(:name).fetch(:first_name)
first_name = person.dig(:name, :first_name)

Other

• OpenStruct
• Singleton
• Observable
• Monitor
• Comparable

May Be Useful

• TSort

Run

Library

• un

How To Use

ruby [switches] [--] [programfile] [arguments]

  -rlibrary       require the library before executing your script
  -e 'command'    one line of script. Several -e's allowed.

ruby -run -e COMMAND [--] [OPTIONS]

Note: POSIX Utility Syntax Guideline 10:

Guideline 10:    The argument "--" should be accepted as a delimiter
                 indicating the end of options.  Any following
                 arguments should be treated as operands, even if they
                 begin with the '-' character.  The "--" argument
                 should not be used as an option or as an operand.

Examples

help

ruby -run -e help [COMMAND]
ruby -run -e help

httpd

ruby -run -e httpd -- [OPTION] DocumentRoot
ruby -run -e httpd -- .
ruby -run -e httpd -- --port 8000 .