From: "David A. Black" <dblack@...>
Date: 2005-10-28T23:16:44+09:00
Subject: Re: Cleaner syntax for .map (is there already a way, or ruby2 idea?)

Hi --

On Fri, 28 Oct 2005, Daniel Schierbeck wrote:

> David A. Black wrote:
>> Hi --
>> 
>> On Fri, 28 Oct 2005, Daniel Schierbeck wrote:
>> 
>>> Daniel Schierbeck wrote:
>>> 
>>>> David A. Black wrote:
>>>> 
>>>>> I know that people.every could return
>>>>> some kind of generator or enumerator, which could then be fed
>>>>> "email_addr" symbolically... 
>>>> 
>>>> 
>>>> 
>>>> 
>>>> module Enumerable
>>>>   def every
>>>>     enum, obj = self, Object.new
>>>>     obj.define_method :method_missing do |name, *args|
>>>>       enum.map { |element| element.send(name, *args) }
>> 
>> 
>> If you must do this, you'd probably want each rather than map there.
>
> Nope. I wan't it to return an array of the values returned.

Oh right, never mind.

>  ["john", "sylvia", "sarah"].every.upcase -> ["JOHN", "SYLVIA", "SARAH"]
>
> That's of course not a very good example. This would probably be better:
>
>  addresses = contacts.every.email_addr
>
> As opposed to
>
>  addresses = contacts.collect { |contact| contact.email_addr }

I strongly prefer the latter.  You've gone out of your way to make it
long and wordy :-)

   addresses = contacts.map {|c| c.email_addr }

> But I agree that the dot syntax is bad, I was just proving that it could 
> easily be done. This would be better:
>
>  addresses = contacts.every(:email_addr)

There was an RCR once for enum.map(:method) {|x| ... } but it was
rejected.

> And maybe even have a `with_every' method:
>
>  contacts.with_every(:email_addr) do |email_addr|
>    puts " - " + email_addr
>  end

"with_every" feels like the wrong word, though.  It suggests that
they're all being used at the same time.  Maybe:

   contacts.each_send(:email_addr)

or something.


David

-- 
David A. Black
dblack@wobblini.net