- •Programming Ruby The Pragmatic Programmer's Guide
- •Foreword
- •Preface
- •Ruby Sparkles
- •What Kind of Language Is Ruby?
- •Is Ruby for Me?
- •Why Did We Write This Book?
- •Ruby Versions
- •Installing Ruby
- •Building Ruby
- •Running Ruby
- •Interactive Ruby
- •Ruby Programs
- •Resources
- •Acknowledgments
- •Notation Conventions
- •Roadmap
- •Ruby.New
- •Ruby Is an Object-Oriented Language
- •Some Basic Ruby
- •Arrays and Hashes
- •Control Structures
- •Regular Expressions
- •Blocks and Iterators
- •Reading and 'Riting
- •Onward and Upward
- •Classes, Objects, and Variables
- •Inheritance and Messages
- •Inheritance and Mixins
- •Objects and Attributes
- •Writable Attributes
- •Virtual Attributes
- •Class Variables and Class Methods
- •Class Variables
- •Class Methods
- •Singletons and Other Constructors
- •Access Control
- •Specifying Access Control
- •Variables
- •Containers, Blocks, and Iterators
- •Containers
- •Implementing a SongList Container
- •Blocks and Iterators
- •Implementing Iterators
- •Blocks for Transactions
- •Blocks Can Be Closures
- •Standard Types
- •Numbers
- •Strings
- •Working with Strings
- •Ranges as Sequences
- •Ranges as Conditions
- •Ranges as Intervals
- •Regular Expressions
- •Patterns
- •Anchors
- •Character Classes
- •Repetition
- •Alternation
- •Grouping
- •Pattern-Based Substitution
- •Backslash Sequences in the Substitution
- •Object-Oriented Regular Expressions
- •More About Methods
- •Defining a Method
- •Variable-Length Argument Lists
- •Methods and Blocks
- •Calling a Method
- •Expanding Arrays in Method Calls
- •Making Blocks More Dynamic
- •Collecting Hash Arguments
- •Expressions
- •Operator Expressions
- •Miscellaneous Expressions
- •Command Expansion
- •Backquotes Are Soft
- •Assignment
- •Parallel Assignment
- •Nested Assignments
- •Other Forms of Assignment
- •Conditional Execution
- •Boolean Expressions
- •Defined?, And, Or, and Not
- •If and Unless Expressions
- •If and Unless Modifiers
- •Case Expressions
- •Iterators
- •Break, Redo, and Next
- •Variable Scope and Loops
- •Exceptions, Catch, and Throw
- •The Exception Class
- •Handling Exceptions
- •Tidying Up
- •Play It Again
- •Raising Exceptions
- •Adding Information to Exceptions
- •Catch and Throw
- •Modules
- •Namespaces
- •Instance Variables in Mixins
- •Iterators and the Enumerable Module
- •Including Other Files
- •Basic Input and Output
- •What Is an io Object?
- •Opening and Closing Files
- •Reading and Writing Files
- •Iterators for Reading
- •Writing to Files
- •Talking to Networks
- •Threads and Processes
- •Multithreading
- •Creating Ruby Threads
- •Manipulating Threads
- •Thread Variables
- •Threads and Exceptions
- •Controlling the Thread Scheduler
- •Mutual Exclusion
- •The Mutex Class
- •Condition Variables
- •Running Multiple Processes
- •Spawning New Processes
- •Independent Children
- •Blocks and Subprocesses
- •When Trouble Strikes
- •Ruby Debugger
- •Interactive Ruby
- •Editor Support
- •But It Doesn't Work!
- •But It's Too Slow!
- •Create Locals Outside Blocks
- •Use the Profiler
- •Ruby and Its World
- •Command-Line Arguments
- •Command-Line Options
- •Program Termination
- •Environment Variables
- •Writing to Environment Variables
- •Where Ruby Finds Its Modules
- •Build Environment
- •Ruby and the Web
- •Writing cgi Scripts
- •Using cgi.Rb
- •Quoting
- •Creating Forms and html
- •Cookies
- •Sessions
- •Embedding Ruby in html
- •Using eruby
- •Installing eruby in Apache
- •Improving Performance
- •Ruby Tk
- •Simple Tk Application
- •Widgets
- •Setting Widget Options
- •Getting Widget Data
- •Setting/Getting Options Dynamically
- •Sample Application
- •Binding Events
- •Scrolling
- •Just One More Thing
- •Translating from Perl/Tk Documentation
- •Object Creation
- •Running Ruby Under Windows
- •Windows Automation
- •Getting and Setting Properties
- •Named Arguments
- •For each
- •An Example
- •Optimizing
- •Extending Ruby
- •Ruby Objects in c
- •Value as a Pointer
- •Value as an Immediate Object
- •Writing Ruby in c
- •Evaluating Ruby Expressions in c
- •Sharing Data Between Ruby and c
- •Directly Sharing Variables
- •Wrapping c Structures
- •An Example
- •Memory Allocation
- •Creating an Extension
- •Creating a Makefile with extconf.Rb
- •Static Linking
- •Embedding a Ruby Interpreter
- •Bridging Ruby to Other Languages
- •Ruby c Language api
- •The Ruby Language
- •Source Layout
- •Begin and end Blocks
- •General Delimited Input
- •The Basic Types
- •Integer and Floating Point Numbers
- •Strings
- •Requirements for a Hash Key
- •Symbols
- •Regular Expressions
- •Regular Expression Options
- •Regular Expression Patterns
- •Substitutions
- •Extensions
- •Variable/Method Ambiguity
- •Variables and Constants
- •Scope of Constants and Variables
- •Predefined Variables
- •Exception Information
- •Pattern Matching Variables
- •Input/Output Variables
- •Execution Environment Variables
- •Standard Objects
- •Global Constants
- •Expressions Single Terms
- •Operator Expressions
- •More on Assignment
- •Parallel Assignment
- •Block Expressions
- •Boolean Expressions
- •Truth Values
- •And, Or, Not, and Defined?
- •Comparison Operators
- •Ranges in Boolean Expressions
- •Regular Expressions in Boolean Expressions
- •While and Until Modifiers
- •Break, Redo, Next, and Retry
- •Method Definition
- •Method Arguments
- •Invoking a Method
- •Class Definition
- •Creating Objects from Classes
- •Class Attribute Declarations
- •Module Definitions
- •Mixins---Including Modules
- •Module Functions
- •Access Control
- •Blocks, Closures, and Proc Objects
- •Proc Objects
- •Exceptions
- •Raising Exceptions
- •Handling Exceptions
- •Retrying a Block
- •Catch and Throw
- •Classes and Objects
- •How Classes and Objects Interact
- •Your Basic, Everyday Object
- •Object-Specific Classes
- •Mixin Modules
- •Extending Objects
- •Class and Module Definitions
- •Class Names Are Constants
- •Inheritance and Visibility
- •Freezing Objects
- •Locking Ruby in the Safe
- •Safe Levels
- •Tainted Objects
- •Reflection, ObjectSpace, and Distributed Ruby
- •Looking at Objects
- •Looking Inside Objects
- •Looking at Classes
- •Looking Inside Classes
- •Calling Methods Dynamically
- •Performance Considerations
- •System Hooks
- •Runtime Callbacks
- •Tracing Your Program's Execution
- •How Did We Get Here?
- •Marshaling and Distributed Ruby
- •Custom Serialization Strategy
- •Distributed Ruby
- •Compile Time? Runtime? Anytime!
- •Standard Library
Creating Forms and html
CGIcontains a huge number of methods used to create HTML---one method per tag. In order to enable these methods, you must create aCGIobject by callingCGI.new, passing in the required level of HTML. For these examples, we'll use ``html3''.
To make tag nesting easier, these methods take their content as code blocks. The code blocks should return a String, which will be used as the content for the tag. For this example, we've added some gratuitous newlines to make the output fit on the page.
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require "cgi" cgi = CGI.new("html3") # add HTML generation methods cgi.out{ cgi.html{ cgi.head{ "\n"+cgi.title{"This Is a Test"} } + cgi.body{ "\n"+ cgi.form{"\n"+ cgi.hr + cgi.h1 { "A Form: " } + "\n"+ cgi.textarea("get_text") +"\n"+ cgi.br + cgi.submit } } } } |
produces:
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Content-Type: text/html Content-Length: 302
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML><HEAD> <TITLE>This Is a Test</TITLE></HEAD><BODY> <FORM ENCTYPE="application/x-www-form-urlencoded" METHOD="post"> <HR><H1>A Form: </H1> <TEXTAREA NAME="get_text" COLS="70" ROWS="10"></TEXTAREA> <BR><INPUT TYPE="submit"></FORM></BODY></HTML> |
This code will produce an HTML form titled ``This Is a Test,'' followed by a horizontal rule, a level-one header, a test input area, and finally a submit button. When the submit comes back, you'll have a CGI parameter named ``get_text'' containing the text the user entered.
Cookies
You can store all kinds of interesting stuff on an unsuspecting surfer's machine using cookies. You can create a named cookie object and store a number of values in it. To send it down to the browser, set a ``cookie'' header in the call toCGI#out.
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require "cgi" cookie = CGI::Cookie.new("rubyweb", "CustID=123", "Part=ABC"); cgi = CGI.new("html3") cgi.out( "cookie" => [cookie] ){ cgi.html{ "\nHTML content here" } } |
produces:
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Content-Type: text/html Content-Length: 86 Set-Cookie: rubyweb=CustID%3D123&Part%3DABC; path=
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML> HTML content here</HTML> |
The next time the user comes back to this page, you can retrieve the cookie values for CustIDandPart, as shown in the HTML output.
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require "cgi" cgi = CGI.new("html3") cgi.out{ cgi.html{ cgi.pre{ cookie = cgi.cookies["rubyweb"] "\nCookies are\n" + cookie.value.join("\n") } } } |
produces:
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Content-Type: text/html Content-Length: 111
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><HTML><PRE> Cookies are CustID=123 Part=ABC</PRE></HTML> |
Sessions
Cookies by themselves still need a bit of work to be useful. What we really want is a session:a persistent state for some Web surfer. Sessions are handled withCGI::Session(documented beginning on page 504), which uses cookies but provides a higher-level abstraction.
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require "cgi" require "cgi/session"
cgi = CGI.new("html3") sess = CGI::Session.new( cgi, "session_key" => "rubyweb", "session_id" => "9650", "new_session" => true, "prefix" => "web-session.") sess["CustID"] = 123 sess["Part"] = "ABC"
cgi.out{ cgi.html{ "\nHTML content here" } } |
This will send a cookie to the user named ``rubyweb'' with a value of 9650. It will also create a disk file in $TMP/web-session.9650with thekey, valuepairs forCustIDandPart.
When the user returns, all you need is a parameter to indicate the session id. In this example, that would be rubyweb=9650. With that value in the parameters, you'll be able to retrieve the full set of saved session data.
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require "cgi" require "cgi/session"
cgi = CGI.new("html3") sess = CGI::Session.new( cgi, "session_key" => "rubyweb", "prefix" => "web-session.") cgi.out{ cgi.html{ "\nCustomer #{sess['CustID']} orders an #{sess['Part']}" } } |