More than one initializer

Ruby
#1

Hi all,

I have a module containing two classes the first is ‘item’ the second is
‘search’. Lets use twitter as an example:
module MyTwitter
class Item
attribute_reader :id, :tweet
def initialize(text)
@tweet = text
# Post to twitter
@id = id_from_post_operation
end
end

class Search
def self.do(q)
# perform search
out = []
results.each do |hit|
# This is the problem point:
out << Item.new_from_data(hit.id,hit.text)
end
return out
end
end
end

When I create a new Item object I have code that creates a new tweet
however I’d like my Search to return an array of Item objects, but if I
use the standard MyTwitter::Item.new I’ll be posting a new item,
not simply creating an object with the id I have from my search.

Is there a way to create an object with a given attribute without
calling .new?

I hope I’ve explained myself well enough! Thanks,
JP

#2

On 27.09.2009 15:07, Jp Hastings-spital wrote:

  @id = id_from_post_operation
  end

Is there a way to create an object with a given attribute without
calling .new?

I hope I’ve explained myself well enough! Thanks,
JP

You could do:

class Item
def self.new_from_data(id, text)
it = allocate
it.id = id
it.text = text
it
end
end

Or change your initialize logic to handle both cases.

Cheers

robert

#3

Hi

  @id = id_from_post_operation
  end

Is there a way to create an object with a given attribute without
calling .new?

You’re probably better off by not making Item.new post a tweet. Instead,
have your initialize method only create an object with id/text
attributes set if they are passed in. Then, create a self.post method to
actually post tweets. It could look like this:

class Item
attribute_reader :id, :tweet
def initialize(id, text)
@id, @tweet = id, text
end
def self.post(text)

Post to twitter

self.new(id_from_post_operation, text)
end

That’ll solve it I hope. By the way, if your items are tweets, it makes
more sense to call the class Tweet rather than Item. And then the @tweet
attribute could be @text, to make it clear as to what it is. the Search
class probably should just be incorporated into the Tweet class, rather
than in a separate class, unless you’re using search across a number of
things and not just tweets. But if your items aren’t tweets, well I’m
just being silly :slight_smile:

#4

Cheers Ehsanul, yeah, they’re not tweets - just an easy way to make the
situation understood! But thanks for your help!

Robert - thanks for the ‘allocate’ tip, that will probably be the way
forward here. However ‘id’ and ‘tweet’ are read-only attributes (and I’d
like them to remain that way):

NoMethodError: undefined method `id=’ for #MyTwitter::Item:0x1019bad50

I think I might play with altering the logic inside .new to
transparently accept id/text as well, seems like the simplest way
forward.

Cheers!
JP