On 25-07-2014 12:20, Benjamin Fleischer wrote:
I was interested to see why Rails.application etc. is a singleton
object, as I was curious about the use-case for this somewhat strange
design-pattern in a dynamic language like Ruby-- the object
encapsulates state, but that state is global, so is it really state?...
I looked into the Rails source from master back through 3.0, and was
surprised to see that even though there is an instance method that
caches the new object, and :new is made private (per the pattern), the
singleton library itself is not used... and yet it is used elsewhere
in the codebase.
I think this is work that Yehuda, Carl, and José mostly did in 3.0
that has mostly been shuffled around a bit.
Its origins appear to be the change from every Rails app having a
Rails::Application to everyone subclassing Rails::Application and it
then becoming 'illegal' to directly instantiate a Rails::Application..
and yet..
Anyone have any insights into this? Or should I ask on stackoverflow? :)
My initial impetus for looking into it, just now, though I'd been
thinking about it occasionally, was Aaron's recent talk at BigDot Ruby
on benchmarking performance, which got me thinking about object
allocation and the Rails singleton.
https://www.youtube.com/watch?v=d2QdITRRMHg
Well, I guess you mean asking why Rails::Application is a singleton
class rather than Rails.application being a singleton object. I'm
curious, why is it relevant whether Rails::Application is a singleton
class or not? Rails.application should always return the same object
regardless, right? Also, I'm curious, why is this related to that talk
(I've watched it yesterday in full and I can't find how it's a related
subject)?
Do you have any use case where you'd want to instantiate
Rails::Application that would be better than inherit a new class?
I'm not saying that a singleton class is the best approach for
Rails::Application, but I can't see any disadvantage for it either.
That's why I'm asking. If you have some use case where you'd think the
singleton class is a problem please let us know.
--
You received this message because you are subscribed to the Google Groups "Ruby on
Rails: Core" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/rubyonrails-core.
For more options, visit https://groups.google.com/d/optout.
