File: README

# README

Path: | README
Last Update: | Thu Aug 26 13:34:00 -0600 2010

# Markaby (Markup as Ruby)

Markaby is a very short bit of code for writing HTML pages in pure Ruby. It is an alternative to ERb which weaves the two languages together. Also a replacement for templating languages which use primitive languages that blend with HTML.

## Using Markaby as a Rails plugin

Write Rails templates in pure Ruby. Example layout:

      html do
        head do
          title 'Products: ' + action_name
          stylesheet_link_tag 'scaffold'
        end

        body do
          p flash[:notice], :style => "color: green"

          self << content_for_layout
        end
      end

## Using Markaby as a Ruby class

Markaby is flaming easy to call from your Ruby classes.

      require 'markaby'

      mab = Markaby::Builder.new
      mab.html do
        head { title "Boats.com" }
        body do
          h1 "Boats.com has great deals"
          ul do
            li "$49 for a canoe"
            li "$39 for a raft"
            li "$29 for a huge boot that floats and can fit 5 people"
          end
        end
      end
      puts mab.to_s

Markaby::Builder.new does take two arguments for passing in variables and a helper object. You can also affix the block right on to the class.

See Markaby::Builder for all of that.

# A Note About `instance_eval`

The Markaby::Builder class is different from the normal Builder class, since it uses `instance_eval` when running blocks. This cleans up the appearance of the Markaby code you write. If `instance_eval` was not used, the code would look like this:

      mab = Markaby::Builder.new
      mab.html do
        mab.head { mab.title "Boats.com" }
        mab.body do
          mab.h1 "Boats.com has great deals"
        end
      end
      puts mab.to_s

So, the advantage is the cleanliness of your code. The disadvantage is that the block will run inside the Markaby::Builder object‘s scope. This means that inside these blocks, `self` will be your Markaby::Builder object. When you use instance variables in these blocks, they will be instance variables of the Markaby::Builder object.

This doesn‘t effect Rails users, but when used in regular Ruby code, it can be a bit disorienting. You are recommended to put your Markaby code in a module where it won‘t mix with anything.

# The Six Steps of Markaby

If you dive right into Markaby, it‘ll probably make good sense, but you‘re likely to run into a few kinks. Why not review these six steps and commit them memory so you can really know what you‘re doing?

## 1. Element Classes

Element classes may be added by hooking methods onto container elements:

      div.entry do
        h2.entryTitle 'Son of WebPage'
        div.entrySection %{by Anthony}
        div.entryContent 'Okay, once again, the idea here is ...'
      end

Which results in:

      <div class="entry">
        <h2 class="entryTitle">Son of WebPage</h2>
        <div class="entrySection">by Anthony</div>
        <div class="entryContent">Okay, once again, the idea here is ...</div>
      </div>

## 2. Element IDs

IDs may be added by the use of bang methods:

      div.page! {
        div.content! {
          h1 "A Short Short Saintly Dog"
        }
      }

Which results in:

      <div id="page">
        <div id="content">
          <h1>A Short Short Saintly Dog</h1>
        </div>
      </div>

## 3. Validate Your XHTML 1.0 Output

If you‘d like Markaby to help you assemble valid XHTML documents, you can use the `xhtml_transitional` or `xhtml_strict` methods in place of the normal `html` tag.

      xhtml_strict do
        head { ... }
        body { ... }
      end

This will add the XML instruction and the doctype tag to your document. Also, a character set meta tag will be placed inside your `head` tag.

Now, since Markaby knows which doctype you‘re using, it checks a big list of valid tags and attributes before printing anything.

      >> div :styl => "padding: 10px" do
      >>   img :src => "samorost.jpg"
      >> end
      InvalidHtmlError: no such attribute `styl'

Markaby will also make sure you don‘t use the same element ID twice!

## 4. Escape or No Escape?

Markaby uses a simple convention for escaping stuff: if a string is an argument, it gets escaped. If the string is in a block, it doesn‘t.

This is handy if you‘re using something like RedCloth or RDoc inside an element. Pass the string back through the block and it‘ll skip out of escaping.

      div.comment { RedCloth.new(str).to_html }

But, if we have some raw text that needs escaping, pass it in as an argument:

      div.comment raw_str

One caveat: if you have other tags inside a block, the string passed back will be ignored.

      div.comment {
        div.author "_why"
        div.says "Torpedoooooes!"
        "<div>Silence.</div>"
      }

The final div above won‘t appear in the output. You can‘t mix tag modes like that, friend.

## 5. Auto-stringification

If you end up using any of your Markaby "tags" as a string, the tag won‘t be output. It‘ll be up to you to add the new string back into the HTML output.

This means if you call `to_s`, you‘ll get a string back.

      div.title { "Rock Bottom" + span(" by Robert Wyatt").to_s }

But, when you‘re adding strings in Ruby, `to_s` happens automatically.

      div.title { "Rock Bottom" + span(" by Robert Wyatt") }

Interpolation works fine.

      div.title { "Rock Bottom #{span(" by Robert Wyatt")}" }

And any other operation you might perform on a string.

      div.menu! \
        ['5.gets', 'bits', 'cult', 'inspect', '-h'].map do |category|
          link_to category
        end.
        join( " | " )

## 6. The `tag!` Method

If you need to force a tag at any time, call `tag!` with the tag name followed by the possible arguments and block. The CssProxy won‘t work with this technique.

      tag! :select, :id => "country_list" do
        countries.each do |country|
          tag! :option, country
        end
      end

# A Note About Rails Helpers

When used in Rails templates, the Rails helper object is passed into Markaby::Builder. When you call helper methods inside Markaby, the output from those methods will be output to the stream. This is incredibly handy, since most Rails helpers output HTML tags.

      head do
        javascript_include_tag 'prototype'
        autodiscovery_link_tag
      end

However, some methods are designed to give back a String which you can use elsewhere. That‘s okay! Every method returns a Fragment object, which can be used as a string.

      p { "Total is: #{number_to_human_size @file_bytes}" }

Also see the Quick Tour above, specifically the stuff about auto-stringification.

If for any reason you have trouble with fragments, you can just call the `@helpers` object with the method and you‘ll get the String back and nothing will be output.

      p { "Total is: #{@helper.number_to_human_size @file_bytes}" }

Conversely, you may call instance variables from your controller by using a method and its value will be returned, nothing will be output.

      # Inside imaginary ProductController
      def list
        @products = Product.find :all
      end

      # Inside app/views/product/list.mab
      products.each do |product|
        p product.title
      end

# Credits

Markaby is a work of immense hope by Tim Fletcher and why the lucky stiff. Thankyou for giving it a whirl.

Markaby is inspired by the HTML library within cgi.rb. Hopefully it will turn around and take some cues.

[Validate]