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dir = File.dirname(__FILE__)
require "#{dir}/page"
require "#{dir}/sidebar"
require "#{dir}/article"
require "#{dir}/section"
class Userguide < Page
def initialize
super(:page_title => "User Guide")
end
def render_body
p do
text "Make sure to check out the "
a "RDoc Documentation", :href => "rdoc"
text " for more details on the API."
end
widget article
end
def article
Article.new(
[
Section.new("The Basics") do
p "The basic way to construct some HTML/XML with erector is to subclass Erector::Widget and implement a content method:"
table do
tr do
td do
pre <<DONE
class Hello < Erector::Widget
def content
html do
head do
title "Hello"
end
body do
text "Hello, "
b "world!"
end
end
end
end
DONE
end
td do
span :class => "separator" do
text character(:rightwards_arrow)
end
end
td do
pre <<DONE
<html>
<head>
<title>Hello</title>
</head>
<body>
Hello, <b>world!</b>
</body>
</html>
DONE
end
end
end
p do
text "Once you have a widget class, you can instantiate it and then call its "
code "to_html"
text " method."
text " If you want to pass in 'locals' (aka 'assigns'), then do so in the constructor's default hash. This will make instance variables of the same name, with Ruby's '@' sign."
end
pre <<-PRE
class Email < Erector::Widget
def content
a @address, :href => "mailto:#{@address}"
end
end
>> Email.new(:address => "foo@example.com").to_html
=> "<a href=\"mailto:foo@example.com\">foo@example.com</a>"
PRE
p do
text "(If you want control over which locals are valid to be passed in to a widget, use the "
a "needs", :href => "#needs"
text " macro.)"
end
end,
Section.new("Mixin") do
p "If all this widget stuff is too complicated, just do "
pre "include Erector::Mixin"
p do
text "and then call "
code "erector { }"
text " from anywhere in your code. It will make an "
a "inline widget", :href => "#inline"
text " for you, pass in the block, and call "
code "to_html"
text " on it. And if you pass any options to "
code "erector"
text ", like "
code ":prettyprint => true"
text ", it'll pass them along to "
code "to_html"
text "!"
end
h3 "Examples:"
pre <<-PRE
erector { a "lols", :href => "http://icanhascheezburger.com/" }
=> "<a href=\\"http://icanhascheezburger.com/\\">lols</a>"
erector(:prettyprint => true) do
ol do
li "bacon"
li "lettuce"
li "tomato"
end
end
=> "<ol>\\n <li>bacon</li>\\n <li>lettuce</li>\\n <li>tomato</li>\\n</ol>\\n"
PRE
end,
Section.new("API Cheatsheet") do
cheats = [
["element('foo')", "<foo></foo>"],
["empty_element('foo')", "<foo />"],
["html", "<html></html>", "and likewise for all non-deprecated elements from the HTML 4.0.1 spec"],
["b 'foo'", "<b>foo</b>"],
["div { b 'foo' }", "<div><b>foo</b></div>"],
["text 'foo'", "foo"],
["text '&<>'", "&amp;&lt;&gt;", "all normal text is HTML escaped, which is what you generally want, especially if the text came from the user or a database"],
["text raw('&<>')", "&<>", "raw text escapes being escaped"],
["rawtext('&<>')", "&<>", "alias for text(raw())"],
["text!('&<>')", "&<>", "another alias for text(raw())"],
["div { text 'foo' }", "<div>foo</div>"],
["div 'foo'", "<div>foo</div>"],
["foo = 'bar'\ndiv foo", "<div>bar</div>"],
["a(:href => 'foo.div')", "<a href=\"foo.div\"></a>"],
["a(:href => 'q?a&b')", "<a href=\"q?a&amp;b\"></a>", "attributes are escaped like text is"],
["a(:href => raw('&amp;'))", "<a href=\"&amp;\"></a>", "raw strings are never escaped, even in attributes"],
["a 'foo', :href => \"bar\"", "<a href=\"bar\">foo</a>"],
["text nbsp('Save Doc')", "Save&#160;Doc", "turns spaces into non-breaking spaces"],
["text nbsp", "&#160;", "a single non-breaking space"],
["text character(160)", "&#xa0;", "output a character given its unicode code point"],
["text character(:right-arrow)", "&#x2192;", "output a character given its unicode name"],
["instruct", "<?xml version=\"1.0\" encoding=\"UTF-8\"?>"],
["comment 'foo'", "<!--foo-->"],
["url 'http://example.com'", "<a href=\"http://example.com\">http://example.com</a>"],
["capture { div }", "<div></div>", "returns the block as a string, doesn't add it to the current output stream"],
["div :class => ['a', 'b']", "<div class=\"a b\"></div>"],
]
cheats << [
"javascript(\n" +
"'if (x < y && x > z) \n" +
'alert("don\'t stop");' +
')', <<-DONE
<script type="text/javascript">
// <![CDATA[
if (x < y && x > z) alert("don't stop");
// ]]>
</script>
DONE
]
cheats << [
"jquery '$(\"p\").wrap(\"<div></div>\");'",
<<-DONE
<script type="text/javascript">
// <![CDATA[
jQuery(document).ready(function($){
$("p").wrap("<div></div>");
});
// ]]>
</script>
DONE
]
cheats << ["join([widget1, widget2],\n separator)", "", "See examples/join.rb for more explanation"]
table :class => 'cheatsheet' do
tr do
th "code"
th "output"
end
cheats.each do |cheat|
tr do
td :width=>"30%" do
code do
join cheat[0].split("\n"), raw("<br/>")
end
end
td do
if cheat[1]
code do
join cheat[1].split("\n"), raw("<br/>")
end
end
if cheat[2]
text nbsp(" ")
text character(:horizontal_ellipsis)
i cheat[2]
end
end
end
end
end
p do
text "Lots more documentation is at the "
a "RDoc API pages", :href => "rdoc/index.html"
text " especially for "
a "Erector::Widget", :href => "rdoc/classes/Erector/Widget.html"
text " so don't go saying we never wrote you nothin'."
end
end,
Section.new("Pretty-printing") do
p "Erector has the ability to insert newlines and indentation to make the generated HTML more readable. Newlines are inserted before and after certain tags."
p "To enable pretty-printing (insertion of newlines and indentation) of Erector's output, do one of the following:"
ul do
li do
text "call "
code "to_pretty"
text " instead of "
code "to_html"
text " on your Erector::Widget"
end
li do
text "pass "
code ":prettyprint => true"
text " to "
code "to_html"
end
li do
text "call "
code "enable_prettyprint(true)"
text " on your Erector::Widget. Then subsequent calls to to_html will prettyprint"
end
li do
text "call "
code "Erector::Widget.prettyprint_default = true"
text " (for example, in environments/development.rb in a rails application, or anywhere which is convenient)"
end
end
end,
Section.new("Using Erector from Ruby on Rails", "rails") do
p do
text "Your views are just ruby classes. Your controller can either call Rails' "
code "render :template"
text " method as usual, or directly instantiate the view class and call its content method."
end
p "For example:"
code "app/controllers/welcome_controller.rb:"
pre <<DONE
class WelcomeController < ApplicationController
def index
render :template => 'welcome/show'
end
end
DONE
code "app/views/welcome/show.rb:"
pre <<DONE
class Views::Welcome::Show < Erector::Widget
def content
html do
head do
title "Welcome page"
end
body do
p "Hello, world"
end
end
end
end
DONE
p do
text "For Rails to find these .rb files during "
code "render :template"
text ", you must first either copy the erector source to "
code "vendor/plugins/erector"
text ", or add "
code "require 'erector'"
text " to "
code "config/environment.rb"
text ". You also should delete (or rename) any other view files with the same base name that might be getting in the way."
end
p do
text "Currently there is only partial support for some standard Rails features like partials, layouts, assigns, and helpers. Check the "
a "erector Google Groups mailing list", :href => "http://googlegroups.com/group/erector"
text " for status updates on these features."
end
end,
Section.new("Erector tool: Command-line conversion to and from HTML", "tool") do
p """
To make Rails integration as smooth as possible, we've written a little tool that will help you
erect your existing Rails app. The 'erector' tool will convert HTML or HTML/ERB into an Erector class.
It ships as part of the Erector gem, so to try it out, install the gem, then run
""".strip
pre "erector app/views/foos/*.html.erb"
p "or just"
pre "erector app/views"
p "and then delete the original files when you're satisfied."
p "Here's a little command-line howto for erecting a scaffold Rails app:"
pre <<DONE
rails foo
cd foo
script/generate scaffold post title:string body:text published:boolean
erector app/views/posts
mate app/views/posts
sleep 30 # this should be enough time for you to stop drooling
rm app/views/posts/*.erb
(echo ""; echo "require 'erector'") >> config/environment.rb
rake db:migrate
script/server
open http://localhost:3000/posts
DONE
p do
text "On the erector-to-html side, pass in the "
code "--to-html"
text "option and some file names and it will render the erector widgets to appropriately-named HTML files."
text " We're actually using "
code "erector"
text " to build this Erector documentation web site that you're reading "
b "right now."
text " Check out the 'web' directory and the 'web' task in the Rakefile to see how it's done."
end
end,
Section.new("Layout Inheritance") do
p "Erector replaces the typical Rails layout mechanism with a more natural construct, the use of inheritance. Want a common
layout? Just implement a layout superclass and inherit from it. Implement content in the superclass and implement template
methods in its subclasses."
p do
text "For example:"
pre <<-DONE
class Views::Layouts::Page < Erector::Widget
def content
html do
head do
title "MyApp - \#{page_title}"
css "myapp.css"
end
body do
div :class => 'sidebar' do
render_sidebar
end
div :class => 'body' do
render_body
end
div :class => 'footer' do
render_footer
end
end
end
end
def render_sidebar
a "MyApp Home", :href => "/"
end
def render_body
p "This page intentionally left blank."
end
def render_footer
p "Copyright (c) 2112, Rush Enterprises Inc."
end
end
DONE
pre <<-DONE
class Views::Faq::Index < Views::Layouts::Page
def initialize
super(:page_title => "FAQ")
end
def render_body
p "Q: Why is the sky blue?"
p "A: To get to the other side"
end
def render_sidebar
super
a "More FAQs", :href => "http://faqs.org"
end
end
DONE
end
p "Notice how this mechanism allows you to..."
ul do
li "Set instance variables (e.g. title)"
li "Override sections completely (e.g. render_body)"
li "Append to standard content (e.g. render_sidebar)"
li "Use standard content unchanged (e.g. render_footer)"
end
p "all in a straightforward, easily understood paradigm (OO inheritance). (No more weird yielding to invisible, undocumented closures!)"
p do
text "To use this in Rails, declare "
code "layout nil"
text " in "
code "app/controllers/application.rb"
text " and then define your Page parent class as "
code "class Views::Layouts::Page"
text " in "
code "app/views/layouts"
text " as usual."
end
p "There's one trick you'll need to use this layout for non-erector view templates. Here's an example."
p do
code "application.rb"
text " - The Erector layout superclass"
pre <<DONE
class Views::Layouts::Application < Erector::Widget
attr_accessor :content
def content
html do
head { } # head content here
# body content here
body do
text content
end
end
end
end
DONE
end
p do
code "application.mab"
text " - The markaby template (adjust for other appropriately templating technologies)"
pre <<DONE
widget = Views::Layouts::Application.new(self)
widget.content = content_for_layout
self << widget.to_html
DONE
end
p do
text "Here the abstract layout widget is used in a concrete fashion by the template-based layout. Normally, the "
code "content"
text " method would be implemented by subclassing widgets, but the layout template sets it directly and then calls "
code "to_html"
text " on the layout widget. This allows the same layout to be shared in a backward compatible way."
end
end,
Section.new("Inline Widgets", "inline") do
p do
text "Instead of subclassing "
code "Erector::Widget"
text " and implementing a "
code "content"
text " method, you can pass a block to "
code "Erector.inline"
text " and get back a widget instance you can call to_html on. For example:"
pre <<-DONE
html = Erector.inline do
p "Hello, world!"
end
html.to_html #=> <p>Hello, world!</p>
DONE
text "This lets you define mini-widgets on the fly."
end
p do
text "If you're in Rails, your inline block has access to Rails helpers if you pass a helpers object to to_html:"
pre <<-DONE
html = Erector.inline do
image_tag("/foo")
end
html.to_html(:helpers => controller) #=> <img alt="Foo" src="/foo" />
DONE
end
p do
text "Note that inline widgets are usually redundant if you're already inside an Erector content method. You can just use a normal "
code "do"
text " block and the Erector methods will work as usual when called back from "
code "yield"
text ". Inline widgets get evaluated with "
code "instance_eval"
text " which may or may not be what you want. See the section on "
a "blocks", :href=>"#blocks"
text " in this user guide for more detail."
end
p do
text "One extra bonus feature of inline widgets is that they can call methods defined on the parent class, even though they're out of scope. How do they do this? Through method_missing magic. (But isn't method_missing magic against the design goals of Erector? Yes, some would say so, and that's why we're reserving it for a special subclass and method. For Erector::Widget and subclasses, if you pass in a block, it's a plain old block with normal semantics.) But they can't directly access instance variables on the parent, so watch it."
end
end,
Section.new("Needs") do
p do
text "Named parameters in Ruby are fun, but one frustrating aspect of the 'options hash' technique is that "
text "the code is less self-documenting and doesn't 'fail fast' if you pass in the wrong parameters, "
text "or fail to pass in the right ones. Even simple typos can lead to very annoying debugging problems."
end
p do
text "To help this, we've added an optional feature by which your widget can declare that it "
text "needs a certain set of named parameters to be passed in. "
text "For example:"
pre <<-DONE
class Car < Erector::Widget
needs :engine, :wheels => 4
def content
text "My \#{@wheels} wheels go round and round; my \#{@engine} goes vroom!"
end
end
DONE
text "This widget will throw an exception if you fail to pass "
code ":engine => 'V-8'"
text " into its constructor. (Actually, it will work with any engine, but a V-8 is the baddest.)"
end
p do
text "See the "
a "rdoc for Widget#needs", :href => 'rdoc/classes/Erector/Widget.html#M000053'
text " for more details. Note that as of version 0.7.0, using "
code "needs"
text " no longer automatically declares accessor methods."
end
end,
Section.new("Externals") do
p do
text "Erector's got some nice tags, like "
code "script"
text " and "
code "style"
text ", that you can emit in the content method of your widget. But what if your widget needs something, say a JavaScript library, that should be included not in the main page, but inside the "
code "head"
text " section?"
end
p do
a "Externals", :href => "rdoc/classes/Erector/Externals.html"
text " are a way for your widget to announce to the world that it has an external dependency. It's then up to "
a "another widget", :href => "rdoc/classes/Erector/Widgets/Page.html"
text " to emit that dependency while it's rendering the "
code "head"
text "."
end
p do
text "Here's an example:"
pre <<-DONE
class HotSauce < Erector::Widget
depends_on :css, "/css/tapatio.css"
depends_on :css, "/css/salsa_picante.css", :media => "print"
depends_on :js, "/lib/jquery.js"
depends_on :js, "/lib/picante.js"
def content
p :class => "tapatio" do
text "esta salsa es muy picante!"
end
end
end
DONE
text "Then when "
code "Page"
text " emits the "
code "head"
text " it'll look like this:"
pre <<-DONE
<head>
<meta content="text/html;charset=UTF-8" http-equiv="content-type" />
<title>HotPage</title>
<link href="/css/tapatio.css" media="all" rel="stylesheet" type="text/css" />
<link href="/css/salsa_picante.css" media="print" rel="stylesheet" type="text/css" />
<script src="/lib/jquery.js" type="text/javascript"></script>
<script src="/lib/picante.js" type="text/javascript"></script>
</head>
DONE
end
p do
text "It also collapses redundant externals, so if lots of your widgets declare the same thing (say, 'jquery.js'), it'll only get included once."
end
p do
a "Page", :href => "rdoc/classes/Erector/Widgets/Page.html"
text " looks for the following depends on:"
table do
tr do
th ":js"
td "included JavaScript file"
end
tr do
th ":css"
td "included CSS stylesheet"
end
tr do
th ":script"
td "inline JavaScript"
end
tr do
th ":style"
td "inline CSS style"
end
end
text "It might be a little difficult to remember the difference between :js and :script, and between :css and :style, so I'm thinking of maybe unifying them and looking at the content to determine whether it's inline or not. (Something simple like, if it includes a space, then it's inline.) Good idea? Let us know on "
a "the erector mailing list", :href => "http://googlegroups.com/group/erector"
text "!"
end
p do
text "Instead of a string, you can also specify a File object; the file's contents get read and used as text. This allows you to inline files instead of referring to them, for potential performance benefits."
text " Example:"
pre <<-DONE
depends_on :style, File.new("#{File.dirname(__FILE__)}/../public/sample.css")
DONE
end
end,
Section.new("Blocks") do
p "Erector is all about blocks (otherwise known as closures). Unfortunately, there are some confusing aspects to working with blocks; this section aims to clarify the issues so if you find yourself stuck on an 'undefined method' or a nil instance variable, at least you'll have some context to help debug it."
p "There are basically three cases where you can pass a block to Erector:"
h3 "1. To an element method"
p "This is the normal case that provides the slick HTML DSL. In the following code:"
pre <<-DONE
class Person < Erector::Widget
def content
div do
h3 @name
p do
b "Birthday: "
span @birthday
end
end
end
end
DONE
p do
text "the blocks passed in to "
code "div"
text " and "
code "p"
text " are evaluated using normal "
code "yield"
text " semantics, and the "
code "@name"
text " and "
code "@birthday"
text " instance variables are evaluated in the context of the Person instance being rendered."
end
p "So far, so good."
h3 "2. To the constructor of an Erector::Widget"
p do
text "In this case you can build a widget \"on the fly\" and have it render whatever it wants, then call your block. This is useful for widgets like "
code "Form"
text " which want to wrap your HTML in some of their own tags."
end
pre <<-DONE
class PersonActions < Erector::Widget
needs :user
def content
div do
widget(Form.new(:action => "/person/\#{@user.id}", :method => "delete") do
input :type => "submit", :value => "Remove \#{@user.name}"
end)
widget(Form.new(:action => "/person/\#{@user.id}/email", :method => "post") do
b "Send message: "
input :type => "text", :name => "message"
input :type => "submit", :value => "Email \#{@user.name}"
end)
end
end
end
DONE
p do
text "In this case, you will get two "
code "form"
text " elements, each of which has some boilerplate HTML for emitting the form element, emitting the hidden "
code "_method"
text " input tag in the case of the delete method, then calling back into your widget to emit the contents of the form. In this case, as above, the "
code "@user"
text " instance variable will be sought inside the "
b "calling"
text " widget"
code "(PersonActions)"
text ", not the "
b "called "
text " widget"
code "(Form)"
text "."
end
p do
text "A quirk of this technique is that methods inside the block will be called on the calling widget, not the called widget. This doesn't cause any problems for element methods ("
code "b"
text " and "
code "input"
text " above"
text "), but may be confusing if you want the block to be able to call methods on the target widget. In that case the caller can declare the block to take a parameter; this parameter will point to the nested widget instance."
pre <<-DONE
widget(Form.new(:action => "/person/\#{@user.id}", :method => "delete") do |f|
span "This form's method is \#{f.method}"
input :type => "submit", :value => "Remove \#{@user.name}"
end)
DONE
end
p do
text "(As a variant of this case, note that the"
code "widget"
text " method can accept a widget class, hash and block, instead of an instance; in this case it will set the widget's block and this code:"
pre <<-DONE
widget Form, :action => "/person/\#{@user.id}", :method => "delete" do
input :type => "submit", :value => "Remove \#{@user.name}"
end
DONE
text " will work the same as the version above.)"
end
h3 "3. To the constructor of an Erector::InlineWidget"
p do
text "This is where things get hairy. Sometimes we want to construct a widget on the fly, but we're not inside a widget already. So any block we pass in will not have access to Erector methods. In this case we have a special subclass called "
code "Erector::InlineWidget"
text " which uses two magic tricks: "
code "instance_eval"
text " and "
code "method_missing"
text " to accomplish the following:"
ul do
li do
text "inside the block, "
code "self"
text " points to the widget, not the caller."
end
li do
text "methods will be looked for first on the inline widget, and then on the caller."
end
li do
text "instance variables will be looked for on the inline widget "
b "only"
text ". This can be the source of many a nil! As a general rule, you should probably stay away from instance variables when using inline widgets. However..."
end
li do
b "Bound"
text " local variables will still be in scope. This means you can \"smuggle in\" instance variables via local variables. For example:"
pre <<-DONE
local_name = @name
Page.new do
div local_name
end.to_html
DONE
end
end
p do
text "When using the "
a "mixin", :href => "#mixin"
text ", you get an inline widget, so the above list of tricks applies."
end
hr
p do
text "One note for developers: when creating a widget like "
code "Form"
text " that needs to call back to its block, use the method "
code "call_block"
text ", which calls the block and passes in self as appropriate for both inline and normal widgets."
end
end
end,
])
end
end
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