From: Robert Klemme <shortcutter@...>
Date: 2007-06-29T16:55:06+09:00
Subject: Re: Dynamic sort_by criteria, making it DRY... thanks Robert !

On 29.06.2007 08:12, Josselin wrote:
> On 2007-06-28 23:18:36 +0200, Josselin <josselin@wanadoo.fr> said:
> 
>> On 2007-06-28 13:58:47 +0200, Robert Klemme 
>> <shortcutter@googlemail.com> said:
>>
>>> On 28.06.2007 13:41, Josselin wrote:
>>>> I am presently using a sort_by on my array
>>>>
>>>> =>    buddies = user_buddies.sort_by {|item| item.last_seen_at}
>>>>
>>>> I would like to be able to do the same , based on a variable    
>>>> @criteria   set to the item key to be used
>>>>
>>>> @criteria = 'last_seen_at'   @criteria = 'display_name' ......
>>>>
>>>> =>   buddies = user_buddies.sort_by {|item| item.<@criteria> }
>>>>
>>>> what could be the best way to do it ?
>>>>
>>>> Depending upon another variable @reverse_order = true or false, I 
>>>> would like to perform or not teh reverse! action
>>>>
>>>> => buddies = user_buddies.sort_by {|item| item.last_seen_at}.reverse!
>>>>
>>>> I believe it should be
>>>>
>>>> => buddies =  @reverse_order ? user_buddies.sort_by {|item| 
>>>> item.<@criteria> } : user_buddies.sort_by {|item| item.<@criteria> 
>>>> }.reverse!
>>>>
>>>> thanks for your enlightment !
>>>
>>> buddies = user_buddies.sort_by {|it| it.send @criteria}
>>> buddies.reverse! if @reverse_order
>>>
>>> Kind regards
>>>
>>>     robert
>>
>> Thanks Robert cannot be dryest....  I am so ashame of my solution that 
>> I don't want to publish my code...
> 
> btw , where should I write the 'downcase' method for strings
> 
> I tried to write it into the @criteria   (@criteria = 
> 'display_name.downcase' )
> which seems to be the right place..
> 
> but I got an error
> undefined method `display_name.downcase' for #<User:0x34bc34c>
> 
> thanks for your complementary solution... ;-))
> 
> joss

buddies = user_buddies.sort_by {|it| it.send(@criteria).downcase}

But this works only if you know that all criteria are strings.

Kind regards

	robert