BuildingBlock

Build content programatically with Ruby and Ruby’s blocks.

  require 'facets'
  require 'xmlhelper'

  builder = BuildingBlock.new(XMLHelper, :element)

  doc = builder.html do

    head do
      title "Test"
    end

    body do
      i "Hello"
      br
      text "Test"
      text "Hey"
    end

  end

produces

  <html><head><title>Test</title><body><i>Hello</i><br />TestHey</body></html>

All calls within the block are routed via the Helper Module’s constructor method (element in the above example) unless they are defined by the helper module, in which case they are sent to the helper module directly. The results of these invocations are appended to the output buffer. To prevent this, prefix the method with ‘call_’.

Sometimes keywords can get in the way of a construction. In these cases you can ensure use of constructor method by calling the special build! command. You can also add verbatium text to the output via the #<< operator. Some common Ruby’s built-in methods treated as keywords:

     inspect
     instance_eval
     respond_to?
     singleton_method_undefined
     initialize
     method_missing
     to_str
     to_s

And a few other speciality methods besides:

     to_buffer
     build!
     <<

This work was of course inspired by many great minds, and represents a concise and simple means of accomplishing this pattern of design, which is unique to Ruby.

Constants

ESCAPE: NOTE: When debugging, you may want to add the ‘p’ entry. TODO: There may be other methods that need to be in this exception list.

Public Class Methods

new(dslModule, constructor, output_buffer=nil) click to toggle source

# File lib/buildable.rb, line 234
  def initialize(dslModule, constructor, output_buffer=nil)
    @buffer = output_buffer || ''
    @stack  = []

    @dsl = Class.new{
      include dslModule
    }.new

    @constructor = constructor
  end

Public Instance Methods

<<(s) click to toggle source

Add directly to buffer.

# File lib/buildable.rb, line 289
  def <<(s)
    @buffer << s.to_s
  end

build!(s, *a, &b) click to toggle source

# File lib/buildable.rb, line 247
  def build!(s, *a, &b)
    s = s.to_s

    if b
      @stack << @buffer
      @buffer = ''
      instance_eval(&b)
      out = @buffer
      @buffer = @stack.pop
      a.unshift(out)
    end

    if s =~ /^call_/
      m = s[5..-1].to_sym
      @dsl.send(m, *a, &b).to_s
    elsif @dsl.respond_to?(s) #o =~ /^build_/
      @buffer << @dsl.send(s, *a, &b).to_s
    else
      s = s.chomp('?') if s[-1,1] == '?'
      @buffer << @dsl.send(@constructor, s, *a).to_s
    end
  end

inspect() click to toggle source

Could improve.

# File lib/buildable.rb, line 300
  def inspect
    r = super
    i = r.index(',')
    return r[0...i] + ">"
  end

method_missing(s, *a, &b) click to toggle source

# File lib/buildable.rb, line 272
  def method_missing(s, *a, &b)
    build!(s, *a, &b)
  end

to_buffer() click to toggle source

Return buffer

# File lib/buildable.rb, line 278
  def to_buffer()
    @buffer
  end

to_s() click to toggle source

Return buffer as string.

# File lib/buildable.rb, line 284
  def to_s()   @buffer.to_s   end

to_str() click to toggle source

(Not documented)

# File lib/buildable.rb, line 285
  def to_str() @buffer.to_str end

In Files

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BuildingBlock

BuildingBlock

Constants

Public Class Methods

Public Instance Methods