CachingPresenter has moved

on February 14, 2009 @ 11:03 PM

The new home for CachingPresenter is: http://github.com/mhs/caching_presenter

What is CachingPresenter?

CachingPresenter is a very small presenter pattern implementation in Ruby. In short, the presenter pattern is a technique used to separate presentation logic (aka display logic or view logic) from domain logic and from the view templates themselves. There are a number of reasons this pattern is beneficial when used:

• it stops presentation logic from creeping into domain objects and muddying up their implementation and their business logic
• it stops unnecessary logic from creeping into the views themselves which should be as simple, flexible, and changeable as possible
• it allows you to organize presentation logic in better ways than simply maintaining helper modules that are included everywhere

CachingPresenter seems to be benefit most web-based projects where there is benefit from a separation between the view templates and corresponding presentation logic. It works superbly with Rails, but it is not dependent on Rails. You can use it for any ruby project, web-based or not.

Recent Changes

:requiring is removed in favor of :accepts

The :requiring option has been removed in favor of :accepts. This allows all additional arguments to be optional. For example:

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class NinjaPresenter < CachingPresenter
  presents :ninja, :accepts => [:sword, :agility]
end

# supplying all options
ninja = NinjaPresenter.new :ninja => Ninja.new, :sword => Sword.new, :agility => 100.percent

# supplying only some options, previously this would yell at you for not supplying :agility
ninja = NinjaPresenter.new :ninja => Ninja.new, :sword => Sword.new

Caches hash-reader methods

If a presenter defines the #[] method or if what is being presented on responds to the #[] methods all calls to the presenter using hash-like accessors will successfully be cached. Previously this would die.

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class SamuraiPresenter < CachingPresenter
  presents :samurai, :accepts => [:stats]

  def [](key)
     @stats[key]
  end
end

samurai = SamuraiPresenter.new :samurai, :stats => { :dexterity => 80.percent }
samurai[:dexterity] # => 80.percent

Does not try to cache writer methods

Usually you don’t use writer methods on presenters, but every now and then there is a good reason. Previously, CachingPresenter would completely fail if you writer to define an writer method, now it doesn’t. And it will successfully not be cached.

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class SamuraiPresenter < CachingPresenter
  presents :samurai, :accepts => [:stats]

   # previously this line would have failed miserably
  def sword=(sword)
  end

end

Questions / Docs / Contact / Etc

Any questions, checkout the github page and its corresponding wiki . If all else fails let me know, zach dot dennis at gmail dot com