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  • erb.rb



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The optional filename argument passed to Kernel#eval when the ERB code is run


The Ruby code generated by ERB

Public Class Methods

new(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout') click to toggle source

Constructs a new ERB object with the template specified in str.

An ERB object works by building a chunk of Ruby code that will output the completed template when run. If safe_level is set to a non-nil value, ERB code will be run in a separate thread with $SAFE set to the provided level.

If trim_mode is passed a String containing one or more of the following modifiers, ERB will adjust its code generation as listed:

%  enables Ruby code processing for lines beginning with %
<> omit newline for lines starting with <% and ending in %>
>  omit newline for lines ending in %>

eoutvar can be used to set the name of the variable ERB will build up its output in. This is useful when you need to run multiple ERB templates through the same binding and/or when you want to control where output ends up. Pass the name of the variable to be used inside a String.


require "erb"

# build data class
class Listings
  PRODUCT = { :name => "Chicken Fried Steak",
              :desc => "A well messages pattie, breaded and fried.",
              :cost => 9.95 }

  attr_reader :product, :price

  def initialize( product = "", price = "" )
    @product = product
    @price = price

  def build
    b = binding
    # create and run templates, filling member data variebles"      <%= PRODUCT[:name] %>
      <%= PRODUCT[:desc] %>
".gsub(/^\s+/, ""), 0, "", "@product").result b"      <%= PRODUCT[:name] %> -- <%= PRODUCT[:cost] %>
      <%= PRODUCT[:desc] %>
".gsub(/^\s+/, ""), 0, "", "@price").result b

# setup template data
listings =

puts listings.product + "\n" + listings.price


Chicken Fried Steak
A well messages pattie, breaded and fried.

Chicken Fried Steak -- 9.95
A well messages pattie, breaded and fried.
               # File erb.rb, line 660
def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
  @safe_level = safe_level
  compiler =
  set_eoutvar(compiler, eoutvar)
  @src = compiler.compile(str)
  @filename = nil
version() click to toggle source

Returns revision information for the erb.rb module.

               # File erb.rb, line 242
def self.version
  "erb.rb [2.0.4 #{ERB::Revision.split[1]}]"

Public Instance Methods

result(b=TOPLEVEL_BINDING) click to toggle source

Executes the generated ERB code to produce a completed template, returning the results of that code. (See ERB#new for details on how this process can be affected by safe_level.)

b accepts a Binding or Proc object which is used to set the context of code evaluation.

               # File erb.rb, line 708
def result(b=TOPLEVEL_BINDING)
  if @safe_level
    th = Thread.start { 
      $SAFE = @safe_level
      eval(@src, b, (@filename || '(erb)'), 1)
    return th.value
    return eval(@src, b, (@filename || '(erb)'), 1)
run(b=TOPLEVEL_BINDING) click to toggle source

Generate results and print them. (see #result)

               # File erb.rb, line 696
  print self.result(b)
set_eoutvar(compiler, eoutvar = '_erbout') click to toggle source

Can be used to set eoutvar as described in ERB#new. It’s probably easier to just use the constructor though, since calling this method requires the setup of an ERB compiler object.

               # File erb.rb, line 680
def set_eoutvar(compiler, eoutvar = '_erbout')
  compiler.put_cmd = "#{eoutvar}.concat"
  compiler.insert_cmd = "#{eoutvar}.concat"

  cmd = []
  cmd.push "#{eoutvar} = ''"
  compiler.pre_cmd = cmd

  cmd = []

  compiler.post_cmd = cmd

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