From: Gavin Sinclair <gsinclair@...>
Date: 2004-06-10T14:05:47+09:00
Subject: Re: [ANN] Active Record 0.8.3: Modules, mapping, and transactions

John W. Long wrote:
>> * Create new Active Record objects by setting the attributes through a
>>   block. Like this:
>>
>>     person = Person.new do |p|
>>       p.name = 'Freddy'
>>       p.age  = 19
>>     end
>
> Why is the better than:
>
> person = Person.new(
>      'name' => 'David',
>      'age' => 12
> )

It's easier to type for a start.  Although the aesthetics of it are
subjective, it has some general advantages as an idiom:

 * #initialize doesn't have to do any hash processing to support it

 * since you're calling methods, the behaviour of 'name=' is respected

 * it's self-documenting; you look at the list of attributes of the class
   and know what you can specify in the constructor

As it happens, none of these advantages apply to ActiveRecord: the method 
has to do hash processing anyway, there is no method name= (it's a shallow
method_missing trick), and no attributes are documented.

But it's IMO a good idiom and I'm happy to see it apply to ActiveRecord. 
Note that it takes a single line of code to support:

  yielf self if block_given?

Gavin