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I have a data model and would like to let it be Enumerable. I want to
confirm if this is the way of implementing each and <=> :

def each
@list.each { |item| yield item }
end

def <=>(other)
@list <=> other
end

(let's just assume that @list is an array)

Thanks.
--
Posted via http://www.ruby-forum.com/.

Ruby Rabbit schrieb:
> I have a data model and would like to let it be Enumerable. I want to
> confirm if this is the way of implementing each and <=> :
>
> def each
> @list.each { |item| yield item }
> end
>
> def <=>(other)
> @list <=> other
> end
>
> (let's just assume that @list is an array)
>
> Thanks.
i would define each like this:
def each(&blk)
@list.each(&blk)
end

badboy wrote:
> Ruby Rabbit schrieb:
>>
>> (let's just assume that @list is an array)
>>
>> Thanks.
> i would define each like this:
> def each(&blk)
> @list.each(&blk)
> end

okay, i forgot to mention that I was wondering whether the
easiest/cleanest way was to use a send somehow?

def each
@list.send
end

Actually, since the ruby source is in 'C' one can't check it to see
examples. I searched a lot but came up with nothing.

Thanks.
--
Posted via http://www.ruby-forum.com/.

Ruby Rabbit schrieb:
> badboy wrote:
>> Ruby Rabbit schrieb:
>>> (let's just assume that @list is an array)
>>>
>>> Thanks.
>> i would define each like this:
>> def each(&blk)
>> @list.each(&blk)
>> end
>
> okay, i forgot to mention that I was wondering whether the
> easiest/cleanest way was to use a send somehow?
>
> def each
> @list.send
> end
>
> Actually, since the ruby source is in 'C' one can't check it to see
> examples. I searched a lot but came up with nothing.
>
> Thanks.
I don't think that using send is easier/cleaner
using @list.each(&blk) is nothing else than sending the message "each"
to @list with blk as a block parameter

On Jan 13, 2009, at 1:08 PM, Ruby Rabbit wrote:

> I have a data model and would like to let it be Enumerable. I want to
> confirm if this is the way of implementing each and <=> :

> ...

> def <=>(other)
> @list <=> other
> end

<=> would normally apply to items in your list, not to the container
itself.

Dave Thomas wrote:
> On Jan 13, 2009, at 1:08 PM, Ruby Rabbit wrote:
>
>> I have a data model and would like to let it be Enumerable. I want to
>> confirm if this is the way of implementing each and <=> :
>
>> ...
>
>> def <=>(other)
>> @list <=> other
>> end
>
> <=> would normally apply to items in your list, not to the container
> itself.

That's whats confusing me. How would i put it?

I am putting in the <=> so this class might be more useful to others. I
haven't got around to using it myself. (I have a base class
ListDataModel with minimal methods and wanted to make it as useful as
possible).
--
Posted via http://www.ruby-forum.com/.

On Tue, 13 Jan 2009 14:15:58 -0500, Ruby Rabbit wrote:

> badboy wrote:
>> Ruby Rabbit schrieb:
>>>
>>> (let's just assume that @list is an array)
>>>
>>> Thanks.
>> i would define each like this:
>> def each(&blk)
>> @list.each(&blk)
>> end
>
> okay, i forgot to mention that I was wondering whether the
> easiest/cleanest way was to use a send somehow?
>
> def each
> @list.send
> end

No. This won't work. Send is just a method for calling methods, and
unless you pass it a method name and all relevant arguments, it won't
know what message to send.

Thus, you'll be at

def each &blk
@list.send :each, &blk
end

and it's easier to do

def each &blk
@list.each &blk
end

--Ken


--
Chanoch (Ken) Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/

On Tue, 13 Jan 2009 15:30:20 -0500, Ruby Rabbit wrote:
> I am putting in the <=> so this class might be more useful to others. I
> haven't got around to using it myself. (I have a base class
> ListDataModel with minimal methods and wanted to make it as useful as
> possible).

Is there sume useful comparison for comparing two different data models
with each other? If not, then don't define <=>.

--Ken

--
Chanoch (Ken) Bloom. PhD candidate. Linguistic Cognition Laboratory.
Department of Computer Science. Illinois Institute of Technology.
http://www.iit.edu/~kbloom1/

> Thus, you'll be at
>
> def each &blk
> @list.send :each, &blk
> end
>
> and it's easier to do
>
> def each &blk
> @list.each &blk
> end
>
> --Ken

thanks, (I did forget to put the :each in the lines i put)

> Is there sume useful comparison for comparing two different data models
> with each other? If not, then don't define <=>.

No, not at all. Thanks again.
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Ruby Rabbit wrote:
> def <=>(other)
> @list <=> other
> end

Perhaps you mean something like this:

include Comparable
def <=>(other)
@list <=> other.list # or some other way to order them
end

Making your objects Comparable is distinct from making them Enumerable.
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