Class: ERB

Inherits:
Object
  • Object
show all
Defined in:
lib/erb.rb,
lib/erb.rb,
lib/erb.rb,
lib/erb.rb,
lib/erb.rb

Overview

– ERB::DefMethod

Defined Under Namespace

Modules: DefMethod, Util Classes: Compiler

Constant Summary

Revision =

:nodoc: #'

'$Date:: 2015-12-20 15:36:57 +0900#$'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str, safe_level = nil, trim_mode = nil, eoutvar = '_erbout') ⇒ ERB

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 %>
-  omit blank 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.


797
798
799
800
801
802
803
804
# File 'lib/erb.rb', line 797

def initialize(str, safe_level=nil, trim_mode=nil, eoutvar='_erbout')
  @safe_level = safe_level
  compiler = make_compiler(trim_mode)
  set_eoutvar(compiler, eoutvar)
  @src, @encoding = *compiler.compile(str)
  @filename = nil
  @lineno = 0
end

Instance Attribute Details

#encodingObject (readonly)

The encoding to eval



817
818
819
# File 'lib/erb.rb', line 817

def encoding
  @encoding
end

#filenameObject

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



821
822
823
# File 'lib/erb.rb', line 821

def filename
  @filename
end

#linenoObject

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



825
826
827
# File 'lib/erb.rb', line 825

def lineno
  @lineno
end

#srcObject (readonly)

The Ruby code generated by ERB



814
815
816
# File 'lib/erb.rb', line 814

def src
  @src
end

Class Method Details

.versionObject

Returns revision information for the erb.rb module.



265
266
267
# File 'lib/erb.rb', line 265

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

Instance Method Details

#def_class(superklass = Object, methodname = 'result') ⇒ Object

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()


921
922
923
924
925
# File 'lib/erb.rb', line 921

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)') ⇒ Object

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)


884
885
886
887
888
889
890
# File 'lib/erb.rb', line 884

def def_method(mod, methodname, fname='(ERB)')
  src = self.src
  magic_comment = "#coding:#{@encoding}\n"
  mod.module_eval do
    eval(magic_comment + "def #{methodname}\n" + src + "\nend\n", binding, fname, -2)
  end
end

#def_module(methodname = 'erb') ⇒ Object

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


902
903
904
905
906
# File 'lib/erb.rb', line 902

def def_module(methodname='erb')
  mod = Module.new
  def_method(mod, methodname, @filename || '(ERB)')
  mod
end

#location=(filename, lineno) ⇒ Object



827
828
829
830
# File 'lib/erb.rb', line 827

def location=((filename, lineno))
  @filename = filename
  @lineno = lineno if lineno
end

#make_compiler(trim_mode) ⇒ Object

Creates a new compiler for ERB. See ERB::Compiler.new for details



809
810
811
# File 'lib/erb.rb', line 809

def make_compiler(trim_mode)
  ERB::Compiler.new(trim_mode)
end

#result(b = new_toplevel) ⇒ Object

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 object which is used to set the context of code evaluation.



857
858
859
860
861
862
863
864
865
866
# File 'lib/erb.rb', line 857

def result(b=new_toplevel)
  if @safe_level
    proc {
      $SAFE = @safe_level
      eval(@src, b, (@filename || '(erb)'), @lineno)
    }.call
  else
    eval(@src, b, (@filename || '(erb)'), @lineno)
  end
end

#run(b = new_toplevel) ⇒ Object

Generate results and print them. (see ERB#result)



845
846
847
# File 'lib/erb.rb', line 845

def run(b=new_toplevel)
  print self.result(b)
end

#set_eoutvar(compiler, eoutvar = '_erbout') ⇒ Object

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.



837
838
839
840
841
842
# File 'lib/erb.rb', line 837

def set_eoutvar(compiler, eoutvar = '_erbout')
  compiler.put_cmd = "#{eoutvar}.concat"
  compiler.insert_cmd = "#{eoutvar}.concat"
  compiler.pre_cmd = ["#{eoutvar} = ''"]
  compiler.post_cmd = ["#{eoutvar}.force_encoding(__ENCODING__)"]
end