File: README

# README

Path: | README
Last Update: | Tue Aug 12 12:50:57 -0600 2008

# Project: Builder

## Goal

Provide a simple way to create XML markup and data structures.

## Classes

Builder::XmlMarkup: | Generate XML markup notiation
Builder::XmlEvents: | Generate XML events (i.e. SAX-like)

Notes::

- An `Builder::XmlTree` class to generate XML tree (i.e. DOM-like) structures is also planned, but not yet implemented. Also, the events builder is currently lagging the markup builder in features.

## Usage

      require 'rubygems'
      require_gem 'builder', '~> 2.0'

      builder = Builder::XmlMarkup.new
      xml = builder.person { |b| b.name("Jim"); b.phone("555-1234") }
      xml #=> <person><name>Jim</name><phone>555-1234</phone></person>

or

      require 'rubygems'
      require_gem 'builder'

      builder = Builder::XmlMarkup.new(:target=>STDOUT, :indent=>2)
      builder.person { |b| b.name("Jim"); b.phone("555-1234") }
      #
      # Prints:
      # <person>
      #   <name>Jim</name>
      #   <phone>555-1234</phone>
      # </person>

## Compatibility

### Version 2.0.0 Compatibility Changes

Version 2.0.0 introduces automatically escaped attribute values for the first time. Versions prior to 2.0.0 did not insert escape characters into attribute values in the XML markup. This allowed attribute values to explicitly reference entities, which was occasionally used by a small number of developers. Since strings could always be explicitly escaped by hand, this was not a major restriction in functionality.

However, it did suprise most users of builder. Since the body text is normally escaped, everybody expected the attribute values to be escaped as well. Escaped attribute values were the number one support request on the 1.x Builder series.

Starting with Builder version 2.0.0, all attribute values expressed as strings will be processed and the appropriate characters will be escaped (e.g. "&" will be tranlated to "&amp;"). Attribute values that are expressed as Symbol values will not be processed for escaped characters and will be unchanged in output. (Yes, this probably counts as Symbol abuse, but the convention is convenient and flexible).

Example:

      xml = Builder::XmlMarkup.new
      xml.sample(:escaped=>"This&That", :unescaped=>:"Here&amp;There")
      xml.target!  =>
        <sample escaped="This&amp;That" unescaped="Here&amp;There"/>

### Version 1.0.0 Compatibility Changes

Version 1.0.0 introduces some changes that are not backwards compatible with earlier releases of builder. The main areas of incompatibility are:

- Keyword based arguments to `new` (rather than positional based). It was found that a developer would often like to specify indentation without providing an explicit target, or specify a target without indentation. Keyword based arguments handle this situation nicely.
- Builder must now be an explicit target for markup tags. Instead of writing

        xml_markup = Builder::XmlMarkup.new
        xml_markup.div { strong("text") }

  you need to write

        xml_markup = Builder::XmlMarkup.new
        xml_markup.div { xml_markup.strong("text") }

- The builder object is passed as a parameter to all nested markup blocks. This allows you to create a short alias for the builder object that can be used within the block. For example, the previous example can be written as:

        xml_markup = Builder::XmlMarkup.new
        xml_markup.div { |xml| xml.strong("text") }

- If you have both a pre-1.0 and a post-1.0 gem of builder installed, you can choose which version to use through the RubyGems `require_gem` facility.

        require_gem 'builder', "~> 0.0"   # Gets the old version
        require_gem 'builder', "~> 1.0"   # Gets the new version

## Features

- XML Comments are supported …

        xml_markup.comment! "This is a comment"
          #=>  <!-- This is a comment -->

- XML processing instructions are supported …

        xml_markup.instruct! :xml, :version=>"1.0", :encoding=>"UTF-8"
          #=>  <?xml version="1.0" encoding="UTF-8"?>

  If the processing instruction is omitted, it defaults to "xml". When the processing instruction is "xml", the defaults attributes are:

  version: | 1.0
  encoding: | "UTF-8"

- XML entity declarations are now supported to a small degree.

        xml_markup.declare! :DOCTYPE, :chapter, :SYSTEM, "../dtds/chapter.dtd"
          #=>  <!DOCTYPE chapter SYSTEM "../dtds/chapter.dtd">

  The parameters to a declare! method must be either symbols or strings. Symbols are inserted without quotes, and strings are inserted with double quotes. Attribute-like arguments in hashes are not allowed.

  If you need to have an argument to declare! be inserted without quotes, but the arguement does not conform to the typical Ruby syntax for symbols, then use the :"string" form to specify a symbol.

  For example:

        xml_markup.declare! :ELEMENT, :chapter, :"(title,para+)"
          #=>  <!ELEMENT chapter (title,para+)>

  Nested entity declarations are allowed. For example:

        @xml_markup.declare! :DOCTYPE, :chapter do |x|
          x.declare! :ELEMENT, :chapter, :"(title,para+)"
          x.declare! :ELEMENT, :title, :"(#PCDATA)"
          x.declare! :ELEMENT, :para, :"(#PCDATA)"
        end

        #=>

        <!DOCTYPE chapter [
          <!ELEMENT chapter (title,para+)>
          <!ELEMENT title (#PCDATA)>
          <!ELEMENT para (#PCDATA)>
        ]>

- Some support for XML namespaces is now available. If the first argument to a tag call is a symbol, it will be joined to the tag to produce a namespace:tag combination. It is easier to show this than describe it.

       xml.SOAP :Envelope do ... end

  Just put a space before the colon in a namespace to produce the right form for builder (e.g. "`SOAP:Envelope`" => "`xml.SOAP :Envelope`")

- String attribute values are now escaped by default by Builder (NOTE: this is new behavior as of version 2.0).

  However, occasionally you need to use entities in attribute values. Using a symbols (rather than a string) for an attribute value will cause Builder to not run its quoting/escaping algorithm on that particular value.

  (Note: The `escape_attrs` option for builder is now obsolete).

  Example:

        xml = Builder::XmlMarkup.new
        xml.sample(:escaped=>"This&That", :unescaped=>:"Here&amp;There")
        xml.target!  =>
          <sample escaped="This&amp;That" unescaped="Here&amp;There"/>

- UTF-8 Support

  Builder correctly translates UTF-8 characters into valid XML. (New in version 2.0.0). Thanks to Sam Ruby for the translation code.

  Example:

        xml = Builder::Markup.new
        xml.sample("Iñtërnâtiônàl")
        xml.target!  =>
          "<sample>I&#241;t&#235;rn&#226;ti&#244;n&#224;l</sample>"

## Contact

Author: | Jim Weirich
Email: | jim@weirichhouse.org
Home Page: | onestepback.org
License: | MIT Licence (www.opensource.org/licenses/mit-license.html)

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