Class: ERB (Ruby 2.7.2)
Description: Class : ERB - Ruby 2.7.2

### Home Classes Methods

### In Files

- erb.rb

### Parent

Object

### Namespace

- MODULE ERB::DefMethod
- MODULE ERB::Util

### Methods

- ::new
- ::version
- #def_class
- #def_method
- #def_module
- #location=
- #make_compiler
- #result
- #result_with_hash
- #run
- #set_eoutvar

### Class/Module Index

Quicksearch

- ERB
- ERB::DefMethod
- ERB::Util

No matching classes.

# ERB

### Constants

NOT_GIVEN
ZERO_SAFE_LEVELS

### Attributes

encoding[R]

The encoding to eval

filename[RW]

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

lineno[RW]

The optional lineno 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=NOT_GIVEN, legacy_trim_mode=NOT_GIVEN, legacy_eoutvar=NOT_GIVEN, 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 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("      <%= PRODUCT[:name] %>
          <%= PRODUCT[:desc] %>
    ".gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@product").result b
        ERB.new("      <%= PRODUCT[:name] %> -- <%= PRODUCT[:cost] %>
          <%= PRODUCT[:desc] %>
    ".gsub(/^\s+/, ""), trim_mode: "", eoutvar: "@price").result b
      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 808
    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

version() click to toggle source

Returns revision information for the erb.rb module.

                   # File erb.rb, line 261
    def self.version
      "erb.rb [2.2.0 #{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 976
    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 940
    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') 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 957
    def def_module(methodname='erb')
      mod = Module.new
      def_method(mod, methodname, @filename || '(ERB)')
      mod
    end

location=((filename, lineno)) click to toggle source

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

                   # File erb.rb, line 870
    def location=((filename, lineno))
      @filename = filename
      @lineno = lineno if lineno
    end

make_compiler(trim_mode) click to toggle source

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

                   # File erb.rb, line 837
    def make_compiler(trim_mode)
      ERB::Compiler.new(trim_mode)
    end

result(b=new_toplevel) click to toggle source

Executes the generated ERB code to produce a completed template, returning the results of that code. (See ::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.

                   # File erb.rb, line 900
    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) click to toggle source

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

                   # File erb.rb, line 909
    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) click to toggle source

Generate results and print them. (see #result)

                   # File erb.rb, line 888
    def run(b=new_toplevel)
      print self.result(b)
    end

set_eoutvar(compiler, eoutvar = '_erbout') click to toggle source

Can be used to set eoutvar as described in ::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 880
    def set_eoutvar(compiler, eoutvar = '_erbout')
      compiler.put_cmd = "#{eoutvar}.<<"
      compiler.insert_cmd = "#{eoutvar}.<<"
      compiler.pre_cmd = ["#{eoutvar} = +''"]
      compiler.post_cmd = [eoutvar]
    end