Tilt ==== Tilt is a thin interface over a bunch of different Ruby template engines in an attempt to make their usage as generic possible. This is useful for web frameworks, static site generators, and other systems that support multiple template engines but don't want to code for each of them individually. The following features are supported for all template engines (assuming the feature is relevant to the engine): * Custom template evaluation scopes / bindings * Ability to pass locals to template evaluation * Support for passing a block to template evaluation for "yield" * Backtraces with correct filenames and line numbers * Template file caching and reloading * Fast, method-based template source compilation The primary goal is to get all of the things listed above right for all template engines included in the distribution. Support for these template engines is included with the package: ENGINE FILE EXTENSIONS REQUIRED LIBRARIES -------------------------- ----------------------- ---------------------------- ERB .erb, .rhtml none (included ruby stdlib) Interpolated String .str none (included ruby core) Erubis .erb, .rhtml, .erubis erubis Haml .haml haml Sass .sass haml (< 3.1) or sass (>= 3.1) Scss .scss haml (< 3.1) or sass (>= 3.1) Less CSS .less less Builder .builder builder Liquid .liquid liquid RDiscount .markdown, .mkd, .md rdiscount Redcarpet .markdown, .mkd, .md redcarpet BlueCloth .markdown, .mkd, .md bluecloth Kramdown .markdown, .mkd, .md kramdown Maruku .markdown, .mkd, .md maruku RedCloth .textile redcloth RDoc .rdoc rdoc Radius .radius radius Markaby .mab markaby Nokogiri .nokogiri nokogiri CoffeeScript .coffee coffee-script (+ javascript) Creole (Wiki markup) .wiki, .creole creole WikiCloth (Wiki markup) .wiki, .mediawiki, .mw wikicloth Yajl .yajl yajl-ruby These template engines ship with their own Tilt integration: ENGINE FILE EXTENSIONS REQUIRED LIBRARIES -------------------------- ----------------- ---------------------------- Slim .slim slim (>= 0.7) Embedded JavaScript sprockets Embedded CoffeeScript sprockets JST sprockets See [TEMPLATES.md][t] for detailed information on template engine options and supported features. [t]: http://github.com/rtomayko/tilt/blob/master/TEMPLATES.md "Tilt Template Engine Documentation" Basic Usage ----------- Instant gratification: require 'erb' require 'tilt' template = Tilt.new('templates/foo.erb') => # output = template.render => "Hello world!" It's recommended that calling programs explicitly require template engine libraries (like 'erb' above) at load time. Tilt attempts to lazy require the template engine library the first time a template is created but this is prone to error in threaded environments. The `Tilt` module contains generic implementation classes for all supported template engines. Each template class adheres to the same interface for creation and rendering. In the instant gratification example, we let Tilt determine the template implementation class based on the filename, but `Tilt::Template` implementations can also be used directly: template = Tilt::HamlTemplate.new('templates/foo.haml') output = template.render The `render` method takes an optional evaluation scope and locals hash arguments. Here, the template is evaluated within the context of the `Person` object with locals `x` and `y`: template = Tilt::ERBTemplate.new('templates/foo.erb') joe = Person.find('joe') output = template.render(joe, :x => 35, :y => 42) If no scope is provided, the template is evaluated within the context of an object created with `Object.new`. A single `Template` instance's `render` method may be called multiple times with different scope and locals arguments. Continuing the previous example, we render the same compiled template but this time in jane's scope: jane = Person.find('jane') output = template.render(jane, :x => 22, :y => nil) Blocks can be passed to `render` for templates that support running arbitrary ruby code (usually with some form of `yield`). For instance, assuming the following in `foo.erb`: Hey <%= yield %>! The block passed to `render` is called on `yield`: template = Tilt::ERBTemplate.new('foo.erb') template.render { 'Joe' } # => "Hey Joe!" Template Mappings ----------------- The `Tilt` module includes methods for associating template implementation classes with filename patterns and for locating/instantiating template classes based on those associations. The `Tilt::register` method associates a filename pattern with a specific template implementation. To use ERB for files ending in a `.bar` extension: >> Tilt.register Tilt::ERBTemplate, 'bar' >> Tilt.new('views/foo.bar') => # Retrieving the template class for a file or file extension: >> Tilt['foo.bar'] => Tilt::ERBTemplate >> Tilt['haml'] => Tilt::HamlTemplate It's also possible to register template file mappings that are more specific than a file extension. To use Erubis for `bar.erb` but ERB for all other `.erb` files: >> Tilt.register Tilt::ErubisTemplate, 'bar.erb' >> Tilt.new('views/foo.erb') => Tilt::ERBTemplate >> Tilt.new('views/bar.erb') => Tilt::ErubisTemplate The template class is determined by searching for a series of decreasingly specific name patterns. When creating a new template with `Tilt.new('views/foo.html.erb')`, we check for the following template mappings: 1. `views/foo.html.erb` 2. `foo.html.erb` 3. `html.erb` 4. `erb` ### Fallback mode If there are more than one template class registered for a file extension, Tilt will automatically try to load the version that works on your machine: 1. If any of the template engines has been loaded already: Use that one. 2. If not, it will try to initialize each of the classes with an empty template. 3. Tilt will use the first that doesn't raise an exception. 4. If however *all* of them failed, Tilt will raise the exception of the first template engine, since that was the most preferred one. Template classes that were registered *last* would be tried first. Because the Markdown extensions are registered like this: Tilt.register Tilt::BlueClothTemplate, 'md' Tilt.register Tilt::RDiscountTemplate, 'md' Tilt will first try RDiscount and then BlueCloth. You could say that RDiscount has a *higher priority* than BlueCloth. The fallback mode works nicely when you just need to render an ERB or Markdown template, but if you depend on a specific implementation, you should use #prefer: # Prefer BlueCloth for all its registered extensions (markdown, mkd, md) Tilt.prefer Tilt::BlueClothTemplate # Prefer Erubis for .erb only: Tilt.prefer Tilt::ErubisTemplate, 'erb' When a file extension has a preferred template class, Tilt will *always* use that class, even if it raises an exception. Template Compilation -------------------- Tilt compiles generated Ruby source code produced by template engines and reuses it on subsequent template invocations. Benchmarks show this yields a 5x-10x performance increase over evaluating the Ruby source on each invocation. Template compilation is currently supported for these template engines: StringTemplate, ERB, Erubis, Haml, Nokogiri, Builder and Yajl. LICENSE ------- Tilt is Copyright (c) 2010 [Ryan Tomayko](http://tomayko.com/about) and distributed under the MIT license. See the `COPYING` file for more info.