Comments on: Simplifying your Ruby on Rails code: Presenter pattern, cells plugin

By: joost

joost — Thu, 18 Mar 2010 13:22:00 +0000

Replying to myself, here is how to add the presenter specs to autospec. Put the code below in a .autotest file in your project root.

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Autotest.add_hook :initialize do |at|
at.add_mapping(%r%^app/presenters/(.*)\.rb$%) { |_, m|
["spec/presenters/#{m[1]}_spec.rb"]
}
end

By: joost

joost — Thu, 18 Mar 2010 11:10:00 +0000

Nice writeup, I like the simplicity of this particular Presenter.

How would you go about adding its specs to autospec? It doesn’t seem to include them automatically.

By: Rolly

Rolly — Thu, 18 Mar 2010 23:33:00 +0000

Thanks for writing this up.

This technique is really invaluable as your app grows and you end up with small encapsulated bits of logic that are too big/messy for partials/helpers but are also kind of inappropriate for your models and controllers.

I’m really hoping something like this, or a conversion of Merb Parts, finds its way into Rails 3.

By: Emmanuel Gomez

Emmanuel Gomez — Thu, 18 Mar 2010 03:26:00 +0000

@alexey: one big advantage that Cells (and other ‘heavier’ approaches) have over helpers/partials is inheritance.

The example in this article may not be sufficiently complex to justify for inheritance between Cells, but believe me that this can tremendously simplify an app (compared with complex shared view partials).

By: Ennuyer.net » Blog Archive » Rails Reading - November 1, 2009

Ennuyer.net » Blog Archive » Rails Reading - November 1, 2009 — Thu, 18 Mar 2010 13:25:00 +0000

[...] Simplifying your Ruby on Rails code: Presenter pattern, cells plugin | Dmytro Shteflyuk’s Hom… [...]

By: Alexey Trofimenko

Alexey Trofimenko — Thu, 18 Mar 2010 03:35:00 +0000

one thing I especially love in ruby, you don’t have to think about “patterns” at all. You just write ruby code and use one of them almost intuitivelly, without even remembering it got a big chapter in some Big Java/C++ Book and a Captial Letter Starting Name.

Representers, Proxies, Factories, whatever, sometimes what you’ll get is just another level of abstraction, not really useful at all on a second thought. Please, don’t bring that hell to ruby.

Back to subject: Long time ago we had components, but then world was filled with rumours about them being “slow”, and suddenly they fell out of usage and rails core. I yet to see them reintroduced back, in core, lightweight and isolated, but meanwhile both representers and cells functionality could be easily achieved using helpers alone, and I do it all the time.

differences are:

1) you have the same namespace for @vars (but locals are just as good) and helper names. It’s a bad thing because of possible nameclashes, but it’s a good thing for ctags and grep users. <%= video_link @video, :style => :brief %> is DRY enough

2) you’ll get ActionView::TemplateError with 500 status instead of 404 ActiveRecord::NotFound if you trigger some faulty Model.find in helper and not in controller, but it’s not a big deal and it could be fixed by several plugins.

3) there’s no default place for such helpers, so what i have to do is just to group “presenter helpers” and “cell and decoration helpers” in different helper modules or in different sections of same “resource specific” helper module.

By: Mislav

Mislav — Thu, 18 Mar 2010 20:48:00 +0000

It seems to me that “cells” offer no compelling advantage over simply using presenters with Rails partials.

By: Dmytro Shteflyuk

Dmytro Shteflyuk — Thu, 18 Mar 2010 10:32:00 +0000

You’re welcome :-) Think, author will accept your pull request quickly.

By: Evgeniy Dolzhenko

Evgeniy Dolzhenko — Thu, 18 Mar 2010 09:09:00 +0000

Doh :) sorry then,
Btw. is there anything that prevents adding such a semantics?

From a quick look at Cell::View#render it seems that it could be updated to match the Rails version, but can’t be sure about that.

By: Dmytro Shteflyuk

Dmytro Shteflyuk — Thu, 18 Mar 2010 08:57:00 +0000

In cells you should use old good render :partial. In other places I use render 'partial'. Be careful.