class ERB
Attributes
The optional filename argument passed to Kernel#eval when the ERB
code is run
The Ruby code generated by ERB
Public Class Methods
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 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
Public Instance Methods
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 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
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 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
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 lib/missing/erb.rb, line 599 def def_module(methodname='erb') mod = Module.new def_method(mod, methodname, @filename || '(ERB)') mod end
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 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
Generate results and print them. (see ERB#result
)
# File lib/missing/erb.rb, line 551 def run(b=TOPLEVEL_BINDING) print self.result(b) end
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 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