book

Ruby Cookbook, 2nd Edition

by Lucas Carlson, Leonard Richardson

March 2015

Intermediate to advanced

600 pages

21h 54m

English

O'Reilly Media, Inc.

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Preface
Life Is ShortAudienceThe Structure of This BookHow the Code Listings WorkInstalling the SoftwarePlatform Differences, Version Differences, and Other HeadachesOther ResourcesConventions Used in This BookUsing Code ExamplesComments and QuestionsAcknowledgments
Ruby 2.1
1.1. What’s Different Between Ruby 1.8 and 2.1?1.2. YARV (Yet Another Ruby VM) Bytecode Interpreter1.3. Syntax Changes1.4. Keyword Arguments1.5. Performance Enhancements1.6. Refinements1.7. Debugging with DTrace and TracePoint1.8. Module Prepending1.9. New Methods1.10. New Classes1.11. New Standard Libraries1.12. What’s Next?
Strings
2.1. Building a String from Parts2.2. Substituting Variables into Strings2.3. Substituting Variables into an Existing String2.4. Reversing a String by Words or Characters2.5. Representing Unprintable Characters2.6. Converting Between Characters and Values2.7. Converting Between Strings and Symbols2.8. Processing a String One Character at a Time2.9. Processing a String One Word at a Time2.10. Changing the Case of a String2.11. Managing Whitespace2.12. Testing Whether an Object Is String-Like2.13. Getting the Parts of a String You Want2.14. Word-Wrapping Lines of Text2.15. Generating a Succession of Strings2.16. Matching Strings with Regular Expressions2.17. Replacing Multiple Patterns in a Single Pass2.18. Validating an Email Address2.19. Classifying Text with a Bayesian Analyzer
Numbers
3.1. Parsing a Number from a String3.2. Comparing Floating-Point Numbers3.3. Representing Numbers to Arbitrary Precision3.4. Representing Rational Numbers3.5. Generating Random Numbers3.6. Converting Between Numeric Bases3.7. Taking Logarithms3.8. Finding Mean, Median, and Mode3.9. Converting Between Degrees and Radians3.10. Multiplying Matrices3.11. Solving a System of Linear Equations3.12. Using Complex Numbers3.13. Simulating a Subclass of Fixnum3.14. Doing Math with Roman Numbers3.15. Generating a Sequence of Numbers3.16. Generating Prime Numbers3.17. Checking a Credit Card Checksum
Date and Time
4.1. Finding Today’s Date4.2. Parsing Dates, Precisely or Fuzzily4.3. Printing a Date4.4. Iterating Over Dates4.5. Doing Date Arithmetic4.6. Counting the Days Since an Arbitrary Date4.7. Converting Between Time Zones4.8. Checking Whether Daylight Saving Time Is in Effect4.9. Converting Between Time and DateTime Objects4.10. Finding the Day of the Week4.11. Handling Commercial Dates4.12. Running a Code Block Periodically4.13. Waiting a Certain Amount of Time4.14. Adding a Timeout to a Long-Running Operation
Arrays
5.1. Iterating Over an Array5.2. Rearranging Values Without Using Temporary Variables5.3. Stripping Duplicate Elements from an Array5.4. Reversing an Array5.5. Sorting an Array5.6. Ignoring Case When Sorting Strings5.7. Making Sure a Sorted Array Stays Sorted5.8. Summing the Items of an Array5.9. Sorting an Array by Frequency of Appearance5.10. Shuffling an Array5.11. Getting the N Smallest Items of an Array5.12. Building a Hash from an Array5.13. Extracting Portions of Arrays5.14. Computing Set Operations on Arrays5.15. Partitioning or Classifying a Set
Hashes
6.1. Using Symbols as Hash Keys6.2. Creating a Hash with a Default Value6.3. Adding Elements to a Hash6.4. Removing Elements from a Hash6.5. Using an Array or Other Modifiable Object as a Hash Key6.6. Keeping Multiple Values for the Same Hash Key6.7. Iterating Over a Hash6.8. Iterating Over a Hash in Insertion Order6.9. Printing a Hash6.10. Inverting a Hash6.11. Choosing Randomly from a Weighted List6.12. Building a Histogram6.13. Remapping the Keys and Values of a Hash6.14. Extracting Portions of Hashes6.15. Searching a Hash with Regular Expressions
Files and Directories
7.1. Checking to See If a File Exists7.2. Checking Your Access to a File7.3. Changing the Permissions on a File7.4. Seeing When a File Was Last Used7.5. Listing a Directory7.6. Reading the Contents of a File7.7. Writing to a File7.8. Writing to a Temporary File7.9. Picking a Random Line from a File7.10. Comparing Two Files7.11. Performing Random Access on “Read-Once” Input Streams7.12. Walking a Directory Tree7.13. Locking a File7.14. Backing Up to Versioned Filenames7.15. Pretending a String Is a File7.16. Redirecting Standard Input or Output7.17. Processing a Binary File7.18. Deleting a File7.19. Truncating a File7.20. Finding the Files You Want7.21. Finding and Changing the Current Working Directory
Code Blocks and Iteration
8.1. Creating and Invoking a Block8.2. Writing a Method That Accepts a Block8.3. Binding a Block Argument to a Variable8.4. Blocks as Closures: Using Outside Variables Within a Code Block8.5. Writing an Iterator Over a Data Structure8.6. Changing the Way an Object Iterates8.7. Writing Block Methods That Classify or Collect8.8. Stopping an Iteration8.9. Looping Through Multiple Iterables in Parallel8.10. Hiding Setup and Cleanup in a Block Method8.11. Coupling Systems Loosely with Callbacks
Objects and Classes
9.1. Managing Instance Data9.2. Managing Class Data9.3. Checking Class or Module Membership9.4. Writing an Inherited Class9.5. Overloading Methods9.6. Validating and Modifying Attribute Values9.7. Defining a Virtual Attribute9.8. Delegating Method Calls to Another Object9.9. Converting and Coercing Objects to Different Types9.10. Getting a Human-Readable Printout of Any Object9.11. Accepting or Passing a Variable Number of Arguments9.12. Using Keyword Arguments9.13. Calling a Superclass’s Method9.14. Creating an Abstract Method9.15. Freezing an Object to Prevent Changes9.16. Making a Copy of an Object9.17. Declaring Constants9.18. Implementing Class and Singleton Methods9.19. Controlling Access by Making Methods Private

Modules and Namespaces
10.1. Simulating Multiple Inheritance with Mixins10.2. Extending Specific Objects with Modules10.3. Mixing in Class Methods10.4. Implementing Enumerable: Write One Method, Get 48 Free10.5. Avoiding Naming Collisions with Namespaces10.6. Automatically Loading Libraries as Needed10.7. Including Namespaces10.8. Initializing Instance Variables Defined by a Module10.9. Automatically Initializing Mixed-in Modules10.10. Prepending Modules
Reflection and Metaprogramming
11.1. Finding an Object’s Class and Superclass11.2. Listing an Object’s Methods11.3. Listing Methods Unique to an Object11.4. Getting a Reference to a Method11.5. Fixing Bugs in Someone Else’s Class11.6. Listening for Changes to a Class11.7. Checking Whether an Object Has Necessary Attributes11.8. Responding to Calls to Undefined Methods11.9. Automatically Initializing Instance Variables11.10. Avoiding Boilerplate Code with Metaprogramming11.11. Metaprogramming with String Evaluations11.12. Evaluating Code in an Earlier Context11.13. Undefining a Method11.14. Aliasing Methods11.15. Doing Aspect-Oriented Programming11.16. Enforcing Software Contracts
XML and HTML
12.1. Checking That XML Is Well Formed12.2. Extracting Data from a Document’s Tree Structure12.3. Extracting Data While Parsing a Document12.4. Navigating a Document with XPath12.5. Converting an XML Document into a Hash12.6. Validating an XML Document12.7. Substituting XML Entities12.8. Creating and Modifying XML Documents12.9. Compressing Whitespace in an XML Document12.10. Guessing a Document’s Encoding12.11. Converting from One Encoding to Another12.12. Extracting All the URLs from an HTML Document12.13. Transforming Plain Text to HTML12.14. Converting HTML Documents from the Web into Text12.15. Creating a Simple Feed Aggregator
Graphics and Other File Formats
13.1. Thumbnailing Images13.2. Adding Text to an Image13.3. Converting One Image Format to Another13.4. Graphing Data13.5. Adding Graphical Context with Sparklines13.6. Symmetrically Encrypting Data13.7. Parsing Comma-Separated Data13.8. Parsing Not-Quite-Comma-Separated Data13.9. Generating and Parsing Excel Spreadsheets13.10. Compressing and Archiving Files with Gzip and Tar13.11. Reading and Writing ZIP Files13.12. Reading and Writing Configuration Files13.13. Generating PDF Files13.14. Representing Data as MIDI Music
Databases and Persistence
14.1. Serializing Data with YAML14.2. Serializing Data with Marshal14.3. Persisting Objects with Madeleine14.4. Indexing Unstructured Text with SimpleSearch14.5. Indexing Structured Text with Ferret14.6. Using Berkeley DB Databases14.7. Controlling MySQL on Unix14.8. Finding the Number of Rows Returned by a Query14.9. Talking Directly to a MySQL Database14.10. Talking Directly to a PostgreSQL Database14.11. Using Object Relational Mapping with ActiveRecord14.12. Building Queries Programmatically14.13. Validating Data with ActiveRecord14.14. Preventing SQL Injection Attacks14.15. Using Transactions in ActiveRecord14.16. Adding Hooks to Table Events14.17. Adding Taggability with a Database Mixin
Internet Services
15.1. Grabbing the Contents of a Web Page15.2. Making an HTTPS Web Request15.3. Customizing HTTP Request Headers15.4. Performing DNS Queries15.5. Sending Mail15.6. Reading Mail with IMAP15.7. Reading Mail with POP315.8. Being an FTP Client15.9. Being a Telnet Client15.10. Being an SSH Client15.11. Copying a File to Another Machine15.12. Being a BitTorrent Client15.13. Pinging a Machine15.14. Writing an Internet Server15.15. Parsing URLs15.16. Writing a CGI Script15.17. Setting Cookies and Other HTTP Response Headers15.18. Handling File Uploads via CGI15.19. Running Servlets with WEBrick15.20. Creating a Real-World HTTP Client
Web Development: Ruby on Rails
16.1. Writing a Simple Rails Application to Show System Status16.2. Passing Data from the Controller to the View16.3. Creating a Layout for Your Header and Footer16.4. Redirecting to a Different Location16.5. Displaying Templates with Render16.6. Integrating a Database with Your Rails Application16.7. Understanding Pluralization Rules16.8. Creating a Login System16.9. Storing Hashed User Passwords in the Database16.10. Escaping HTML and JavaScript for Display16.11. Setting and Retrieving Session Information16.12. Setting and Retrieving Cookies16.13. Extracting Code into Helper Functions16.14. Refactoring the View into Partial Snippets of Views16.15. Adding Dynamic Effects with script.aculo.us16.16. Generating Forms for Manipulating Model Objects16.17. Creating an Ajax Form16.18. Exposing Web Services on Your Website16.19. Sending Mail with Rails16.20. Automatically Sending Error Messages to Your Email16.21. Documenting Your Website16.22. Unit-Testing Your Website16.23. Using breakpoint in Your Web Application
Web Development: Sinatra
17.1. Developing a Minimalistic Web-Services–Based Application17.2. Writing a Simple Sinatra Application to Show System Status17.3. Creating a Layout for Your Header and Footer17.4. Passing Data from the Controller to the View17.5. Redirecting to a Different Location17.6. Integrating a Database with Your Sinatra Application17.7. Setting Status Codes and Headers17.8. Setting and Retrieving Session Information17.9. Setting and Retrieving Cookies17.10. Sending Mail with Sinatra17.11. Building RESTful Web Services on Your Website17.12. Creating RESTful JavaScript Clients for Your Web Services
Web Services and Distributed Programming
18.1. Searching for Books on Amazon18.2. Finding Photos on Flickr18.3. Writing an XML-RPC Client18.4. Writing a SOAP Client18.5. Writing a SOAP Server18.6. Charging a Credit Card18.7. Finding the Cost to Ship Packages via UPS or FedEx18.8. Sharing a Hash Between Any Number of Computers18.9. Implementing a Distributed Queue18.10. Creating a Shared “Whiteboard”18.11. Securing DRb Services with Access Control Lists18.12. Automatically Discovering DRb Services with Rinda18.13. Proxying Objects That Can’t Be Distributed18.14. Storing Data on Distributed RAM with MemCached18.15. Caching Expensive Results with MemCached18.16. A Remote-Controlled Jukebox
Testing, Debugging, Optimizing, and Documenting
19.1. Running Code Only in Debug Mode19.2. Raising an Exception19.3. Handling an Exception19.4. Retrying After an Exception19.5. Adding Logging to Your Application19.6. Creating and Understanding Tracebacks19.7. Writing Unit Tests19.8. Running Unit Tests19.9. Testing Code That Uses External Resources19.10. Using debug to Inspect and Change the State of Your Application19.11. Documenting Your Application19.12. Profiling Your Application19.13. Benchmarking Competing Solutions19.14. Running Multiple Analysis Tools at Once
Packaging and Distributing Software
20.1. Finding Libraries by Querying Gem Respositories20.2. Installing and Using a Gem20.3. Requiring a Specific Version of a Gem20.4. Uninstalling a Gem20.5. Reading Documentation for Installed Gems20.6. Packaging Your Code as a Gem20.7. Distributing Your Gems20.8. Installing and Creating Standalone Packages with setup.rb
Automating Tasks with Rake
21.1. Automatically Running Unit Tests21.2. Automatically Generating Documentation21.3. Cleaning Up Generated Files21.4. Automatically Building a Gem21.5. Gathering Statistics About Your Code21.6. Publishing Your Documentation21.7. Running Multiple Tasks in Parallel21.8. Creating a Generic Project Rakefile
Multitasking and Multithreading
22.1. Running a Daemon Process on Unix22.2. Creating a Windows Service22.3. Doing Two Things at Once with Threads22.4. Synchronizing Access to an Object22.5. Terminating a Thread22.6. Running a Code Block on Many Objects Simultaneously22.7. Limiting Multithreading with a Thread Pool22.8. Driving an External Process with popen22.9. Capturing the Output and Error Streams from a Unix Shell Command22.10. Controlling a Process on Another Machine22.11. Avoiding Deadlock
User Interface
23.1. Resources23.2. Getting Input One Line at a Time23.3. Getting Input One Character at a Time23.4. Parsing Command-Line Arguments23.5. Testing Whether a Program Is Running Interactively23.6. Setting Up and Tearing Down a Curses Program23.7. Clearing the Screen23.8. Determining Terminal Size23.9. Changing Text Color23.10. Reading a Password23.11. Allowing Input Editing with Readline23.12. Making Your Keyboard Lights Blink23.13. Creating a GUI Application with Tk23.14. Creating a GUI Application with wxRuby23.15. Creating a GUI Application with Ruby/GTK23.16. Using AppleScript to Get User Input
Extending Ruby with Other Languages
24.1. Writing a C Extension for Ruby24.2. Using a C Library from Ruby24.3. Calling a C Library Through SWIG24.4. Writing Inline C in Your Ruby Code24.5. Using Java Libraries with JRuby
System Administration
25.1. Scripting an External Program25.2. Managing Windows Services25.3. Running Code as Another User25.4. Running Periodic Tasks Without cron or at25.5. Deleting Files That Match a Regular Expression25.6. Renaming Files in Bulk25.7. Finding Duplicate Files25.8. Automating Backups25.9. Normalizing Ownership and Permissions in User Directories25.10. Killing All Processes for a Given User25.11. Using Puppet for DevOps System Administration
Index

Overview

Why spend time on coding problems that others have already solved when you could be making real progress on your Ruby project? This updated cookbook provides more than 350 recipes for solving common problems, on topics ranging from basic data structures, classes, and objects, to web development, distributed programming, and multithreading. Revised for Ruby 2.1, each recipe includes a discussion on why and how the solution works.

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