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  • erb.rb

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ERB

Constants

Revision

Attributes

filename[RW]

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

src[R]

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.

Example

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
  end

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

# setup template data
listings = Listings.new
listings.build

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

Generates

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 698
def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
  @safe_level = safe_level
  compiler = ERB::Compiler.new(trim_mode)
  set_eoutvar(compiler, eoutvar)
  @src, @enc = *compiler.compile(str)
  @filename = nil
end
            
version() click to toggle source

Returns revision information for the erb.rb module.

 
               # File erb.rb, line 260
def self.version
  "erb.rb [2.1.0 #{ERB::Revision.split[1]}]"
end
            

Public Instance Methods

def_class(superklass=Object, methodname='result') click to toggle source

Define unnamed class which has methodname as instance method, and return it.

example:

class MyClass_
  def initialize(arg1, arg2)
    @arg1 = arg1;  @arg2 = arg2
  end
end
filename = 'example.rhtml'  # @arg1 and @arg2 are used in example.rhtml
erb = ERB.new(File.read(filename))
erb.filename = filename
MyClass = erb.def_class(MyClass_, 'render()')
print MyClass.new('foo', 123).render()
 
               # File erb.rb, line 801
def def_class(superklass=Object, methodname='result')
  cls = Class.new(superklass)
  def_method(cls, methodname, @filename || '(ERB)')
  cls
end
            
def_method(mod, methodname, fname='(ERB)') click to toggle source

Define methodname as instance method of mod from compiled ruby source.

example:

filename = 'example.rhtml'   # 'arg1' and 'arg2' are used in example.rhtml
erb = ERB.new(File.read(filename))
erb.def_method(MyClass, 'render(arg1, arg2)', filename)
print MyClass.new.render('foo', 123)
 
               # File erb.rb, line 764
def def_method(mod, methodname, fname='(ERB)')
  src = self.src
  magic_comment = "#coding:#{@enc}\n"
  mod.module_eval do
    eval(magic_comment + "def #{methodname}\n" + src + "\nend\n", binding, fname, -2)
  end
end
            
def_module(methodname='erb') click to toggle source

Create unnamed module, define methodname as instance method of it, and return it.

example:

filename = 'example.rhtml'   # 'arg1' and 'arg2' are used in example.rhtml
erb = ERB.new(File.read(filename))
erb.filename = filename
MyModule = erb.def_module('render(arg1, arg2)')
class MyClass
  include MyModule
end
 
               # File erb.rb, line 782
def def_module(methodname='erb')
  mod = Module.new
  def_method(mod, methodname, @filename || '(ERB)')
  mod
end
            
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 746
def result(b=TOPLEVEL_BINDING)
  if @safe_level
    proc {
      $SAFE = @safe_level
      eval(@src, b, (@filename || '(erb)'), 0)
    }.call
  else
    eval(@src, b, (@filename || '(erb)'), 0)
  end
end
            
run(b=TOPLEVEL_BINDING) click to toggle source

Generate results and print them. (see #result)

 
               # File erb.rb, line 734
def run(b=TOPLEVEL_BINDING)
  print self.result(b)
end
            
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 718
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 = []
  cmd.push("#{eoutvar}.force_encoding(__ENCODING__)")

  compiler.post_cmd = cmd
end
            

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