Class: ERB

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

Overview

– ERB::DefMethod

Defined Under Namespace

Modules: DefMethod, Util Classes: Compiler

Instance Attribute 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 %>

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.



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# File 'lib/missing/erb.rb', line 514

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 = *compiler.compile(str)
  @src.push(";" + eoutvar)
  @src = @src.join
  @filename = nil
end

Instance Attribute Details

#filename ⇒ Object

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



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# File 'lib/missing/erb.rb', line 529

def filename
  @filename
end

#src ⇒ Object (readonly)

The Ruby code generated by ERB



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# File 'lib/missing/erb.rb', line 525

def src
  @src
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/missing/erb.rb', line 618

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/missing/erb.rb', line 581

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') ⇒ 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/missing/erb.rb', line 599

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

#result(b = TOPLEVEL_BINDING) ⇒ 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 or Proc object which is used to set the context of code evaluation.



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# File 'lib/missing/erb.rb', line 563

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) ⇒ Object

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



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# File 'lib/missing/erb.rb', line 551

def run(b=TOPLEVEL_BINDING)
  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/missing/erb.rb', line 536

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
end