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.
Install it as a gem
gem install markaby
Using Markaby with Sinatra (1.0+)
get '/foo' do
mab :my_template # my_template.mab in the sinatra view path
end
If you are looking for sinatra support pre 0.7, see github.com/sbfaulkner/sinatra-markaby
A note on Tilt - using markaby with html5 doesn’t quite yet work properly. If you’d like to render a template with html 5, call this at the start of a .mab template:
enable_html5!
Or enable html 5 globally:
Markaby::Builder.class_eval do
@@options = Markaby::Builder::HTML5_OPTIONS
end
Using Markaby with other frameworks
Tilt has a Markaby module, so in principle, any web framework that supports Tilt will also support Markaby. See the appropriate tilt documentation:
http://github.com/rtomayko/tilt
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 affect 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 html5
, xhtml_transitional
or xhtml_strict
methods in place of the normal html
tag.
html5 do
head { ... }
body { ... }
end
This will add the XML instruction and the doctype tag to your document (for xhtml_strict and xhtml_transitional). 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. "_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. \
['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
Credits
Markaby is a work of immense hope by Tim Fletcher and why the lucky stiff. It is maintained by joho, spox, and smtlaissezfaire. 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.
Patches from contributors:
aredridel (Aria Stewart - [email protected])
- Make exceptions inherit from StandardError (f259c0)