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 collapse

Revision =

:nodoc: #'

'$Date::                           $'

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(str, safe_level = NOT_GIVEN, legacy_trim_mode = NOT_GIVEN, legacy_eoutvar = NOT_GIVEN, 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 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+/, ""), trim_mode: "", eoutvar: "@product").result b
      <%= PRODUCT[:name] %>
      <%= PRODUCT[:desc] %>
    END_PRODUCT
    ERB.new(<<-'END_PRICE'.gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@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.

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

def initialize(str, safe_level=NOT_GIVEN, legacy_trim_mode=NOT_GIVEN, legacy_eoutvar=NOT_GIVEN, trim_mode: nil, eoutvar: '_erbout')
  # Complex initializer for $SAFE deprecation at [Feature #14256]. Use keyword arguments to pass trim_mode or eoutvar.
  if safe_level != NOT_GIVEN
    warn 'Passing safe_level with the 2nd argument of ERB.new is deprecated. Do not use it, and specify other arguments as keyword arguments.', uplevel: 1 if $VERBOSE || !ZERO_SAFE_LEVELS.include?(safe_level)
  end
  if legacy_trim_mode != NOT_GIVEN
    warn 'Passing trim_mode with the 3rd argument of ERB.new is deprecated. Use keyword argument like ERB.new(str, trim_mode: ...) instead.', uplevel: 1 if $VERBOSE
    trim_mode = legacy_trim_mode
  end
  if legacy_eoutvar != NOT_GIVEN
    warn 'Passing eoutvar with the 4th argument of ERB.new is deprecated. Use keyword argument like ERB.new(str, eoutvar: ...) instead.', uplevel: 1 if $VERBOSE
    eoutvar = legacy_eoutvar
  end

  compiler = make_compiler(trim_mode)
  set_eoutvar(compiler, eoutvar)
  @src, @encoding, @frozen_string = *compiler.compile(str)
  @filename = nil
  @lineno = 0
  @_init = self.class.singleton_class
end

Instance Attribute Details

#encodingObject (readonly)

The encoding to eval


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

def encoding
  @encoding
end

#filenameObject

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


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# File 'lib/erb.rb', line 850

def filename
  @filename
end

#linenoObject

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


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# File 'lib/erb.rb', line 854

def lineno
  @lineno
end

#srcObject (readonly)

The Ruby code generated by ERB


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# File 'lib/erb.rb', line 843

def src
  @src
end

Class Method Details

.versionObject

Returns revision information for the erb.rb module.


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# File 'lib/erb.rb', line 262

def self.version
  "erb.rb [2.2.0 #{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()

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# File 'lib/erb.rb', line 977

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)

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# File 'lib/erb.rb', line 941

def def_method(mod, methodname, fname='(ERB)')
  src = self.src.sub(/^(?!#|$)/) {"def #{methodname}\n"} << "\nend\n"
  mod.module_eval do
    eval(src, binding, fname, -1)
  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

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# File 'lib/erb.rb', line 958

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

#location=(filename, lineno) ⇒ Object

Sets optional filename and line number that will be used in ERB code evaluation and error reporting. See also #filename= and #lineno=

erb = ERB.new('<%= some_x %>')
erb.render# undefined local variable or method `some_x'
#   from (erb):1


erb.location = ['file.erb', 3]# All subsequent error reporting would use new location

erb.render# undefined local variable or method `some_x'
#   from file.erb:4


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# File 'lib/erb.rb', line 871

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


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# File 'lib/erb.rb', line 838

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.


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# File 'lib/erb.rb', line 901

def result(b=new_toplevel)
  unless @_init.equal?(self.class.singleton_class)
    raise ArgumentError, "not initialized"
  end
  eval(@src, b, (@filename || '(erb)'), @lineno)
end

#result_with_hash(hash) ⇒ Object

Render a template on a new toplevel binding with local variables specified by a Hash object.


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# File 'lib/erb.rb', line 910

def result_with_hash(hash)
  b = new_toplevel(hash.keys)
  hash.each_pair do |key, value|
    b.local_variable_set(key, value)
  end
  result(b)
end

#run(b = new_toplevel) ⇒ Object

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


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# File 'lib/erb.rb', line 889

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.


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# File 'lib/erb.rb', line 881

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