You are previewing The Ruby Programming Language.

The Ruby Programming Language

Cover of The Ruby Programming Language by Yukihiro Matsumoto... Published by O'Reilly Media, Inc.
  1. The Ruby Programming Language
    1. SPECIAL OFFER: Upgrade this ebook with O’Reilly
    2. A Note Regarding Supplemental Files
    3. Preface
      1. Acknowledgments
      2. Conventions Used in This Book
      3. Using Code Examples
      4. How to Contact Us
      5. Safari® Enabled
    4. 1. Introduction
      1. A Tour of Ruby
      2. Try Ruby
      3. About This Book
      4. A Sudoku Solver in Ruby
    5. 2. The Structure and Execution of Ruby Programs
      1. Lexical Structure
      2. Syntactic Structure
      3. File Structure
      4. Program Encoding
      5. Program Execution
    6. 3. Datatypes and Objects
      1. Numbers
      2. Text
      3. Arrays
      4. Hashes
      5. Ranges
      6. Symbols
      7. True, False, and Nil
      8. Objects
    7. 4. Expressions and Operators
      1. Literals and Keyword Literals
      2. Variable References
      3. Constant References
      4. Method Invocations
      5. Assignments
      6. Operators
    8. 5. Statements and Control Structures
      1. Conditionals
      2. Loops
      3. Iterators and Enumerable Objects
      4. Blocks
      5. Altering Control Flow
      6. Exceptions and Exception Handling
      7. BEGIN and END
      8. Threads, Fibers, and Continuations
    9. 6. Methods, Procs, Lambdas, and Closures
      1. Defining Simple Methods
      2. Method Names
      3. Methods and Parentheses
      4. Method Arguments
      5. Procs and Lambdas
      6. Closures
      7. Method Objects
      8. Functional Programming
    10. 7. Classes and Modules
      1. Defining a Simple Class
      2. Method Visibility: Public, Protected, Private
      3. Subclassing and Inheritance
      4. Object Creation and Initialization
      5. Modules
      6. Loading and Requiring Modules
      7. Singleton Methods and the Eigenclass
      8. Method Lookup
      9. Constant Lookup
    11. 8. Reflection and Metaprogramming
      1. Types, Classes, and Modules
      2. Evaluating Strings and Blocks
      3. Variables and Constants
      4. Methods
      5. Hooks
      6. Tracing
      7. ObjectSpace and GC
      8. Custom Control Structures
      9. Missing Methods and Missing Constants
      10. Dynamically Creating Methods
      11. Alias Chaining
      12. Domain-Specific Languages
    12. 9. The Ruby Platform
      1. Strings
      2. Regular Expressions
      3. Numbers and Math
      4. Dates and Times
      5. Collections
      6. Files and Directories
      7. Input/Output
      8. Networking
      9. Threads and Concurrency
    13. 10. The Ruby Environment
      1. Invoking the Ruby Interpreter
      2. The Top-Level Environment
      3. Practical Extraction and Reporting Shortcuts
      4. Calling the OS
      5. Security
    14. Index
    15. About the Authors
    16. Colophon
    17. SPECIAL OFFER: Upgrade this ebook with O’Reilly
O'Reilly logo

The Top-Level Environment

When the Ruby interpreter starts, a number of classes, modules, constants, and global variables and global functions are defined and available for use by programs. The subsections that follow list these predefined features.

Predefined Modules and Classes

When the Ruby 1.8 interpreter starts, the following modules are defined:

Comparable      FileTest        Marshal         Precision
Enumerable      GC              Math            Process
Errno           Kernel          ObjectSpace     Signal

These classes are defined on startup:

Array           File            Method          String
Bignum          Fixnum          Module          Struct
Binding         Float           NilClass        Symbol
Class           Hash            Numeric         Thread
Continuation    IO              Object          ThreadGroup
Data            Integer         Proc            Time
Dir             MatchData       Range           TrueClass
FalseClass      MatchingData    Regexp          UnboundMethod

The following exception classes are also defined:

ArgumentError           NameError               SignalException
EOFError                NoMemoryError           StandardError
Exception               NoMethodError           SyntaxError
FloatDomainError        NotImplementedError     SystemCallError
IOError                 RangeError              SystemExit
IndexError              RegexpError             SystemStackError
Interrupt               RuntimeError            ThreadError
LoadError               ScriptError             TypeError
LocalJumpError          SecurityError           ZeroDivisionError

Ruby 1.9 adds the following modules, classes, and exceptions:

BasicObject     FiberError      Mutex           VM
Fiber           KeyError        StopIteration

You can check the predefined modules, classes, and exceptions in your implementation with code like this:

# Print all modules (excluding classes) puts {|x| eval(x.to_s).instance_of? Module} # Print all classes (excluding exceptions) ...

The best content for your career. Discover unlimited learning on demand for around $1/day.