Rails core - Jul 2012 - Could Ruby Structs be useful to ActiveRecord?

Hello,

recently I ran into Ruby
Structs<http://www.ruby-doc.org/core-1.9.3/Struct.html>.
Some examples:

# Create a structure with a name in StructStruct.new("Customer",
:name, :address)    #=>
Struct::CustomerStruct::Customer.new("Dave", "123 Main")  
#=> #<struct Struct::Customer name="Dave", address="123
Main">
# Create a structure named by its constantCustomer = Struct.new(:name, :address)
#=> CustomerCustomer.new("Dave", "123 Main")          
#=> #<struct Customer name="Dave", address="123
Main">


Automatic key -> symbol, key -> string, key -> method accessing:

Customer = Struct.new(:name, :address, :zip)joe = Customer.new("Joe
Smith", "123 Maple, Anytown NC", 12345)
joe["name"] = "Luke"joe[:zip]   = "90210"
joe.name   #=> "Luke"joe.zip    #=> "90210"

It seems to me it fits Model representation perfectly, so I wonder if a Model
could have advantages being represented by a Struct class (performance,
coherence...).

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The DAO pattern is totally different than the ActiveRecord pattern, so
you probably won''t see anything like this happen inside of AR itself.
Other ORMs may do something like this, though.

If your model is just a struct, then it has no ''domain''
methods...

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What do you mean for ''domain'' methods? Do you mean
validations, etc? They
can be implemented; the model could be a sort of "struct on
steroids"...
something like this:

module ActiveRecord
  class Struct < ::Struct
    def self.find
    end
    def self.all
    end
    # other various implementations
  end
  class StructFor
    def [](table_name)
       # retrieve table column names
       ActiveRecord:::Struct.new(*table_column_names)
    end
  end
end


model: 
class User < ActiveRecord::StructFor[:users] # this returns 
ActiveRStruct.new(:firstname, :lastname, :active)

  def before_save
     # ...
  end

end

Il giorno sabato 21 luglio 2012 22:03:06 UTC+2, Steve Klabnik ha
scritto:
>
> The DAO pattern is totally different than the ActiveRecord pattern, so 
> you probably won''t see anything like this happen inside of AR
itself.
> Other ORMs may do something like this, though. 
>
> If your model is just a struct, then it has no ''domain''
methods...
>
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Yeah, you''d _have_ to do something like that. Then you''re not
implementing the ActiveRecord pattern anymore, so I don''t think
it''d
really be appropriate.
> Active Record uses the most obvious approach, putting data access logic in
the domain object.
>
> - http://martinfowler.com/eaaCatalog/activeRecord.html
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