From: Victor Shepelev <vshepelev@...>
Date: 2006-05-26T15:49:42+09:00
Subject: Re: Method '!='

From: Sam Roberts [mailto:sroberts@uniserve.com]
Sent: Friday, May 26, 2006 9:30 AM
> Quoting vshepelev@imho.com.ua, on Fri, May 26, 2006 at 03:16:20PM +0900:
> > From: Sam Roberts [mailto:sroberts@uniserve.com]
> > Sent: Friday, May 26, 2006 9:11 AM
> > > Quoting vshepelev@imho.com.ua, on Fri, May 26, 2006 at 02:50:27PM
> +0900:
> > > > So, other question: is there way for uniform compare objects by some
> > > > operator? (where operator is either == or != or <, or even include?)
> > >
> > > Perhaps <=>
> >
> > No-no.
> >
> > The point was to do things like this:
> >
> > def filter(object, op, criteria)
> >   object.send op, criteria
> > end
> >
> > filter 'a', :==, 'b'
> > filter 'Ruby', :include?, 'Ru'
> > filter 110, :<, 15
> >
> > #filter 'a', :!=, 'b' <== doesn't work! :(
> 
> Ok, I see.
> 
> Probably, its because you are showing us a small piece of a larger puzzle,
> but
> why not have filter take a block:
> 
>   def filter(object, op, criteria)
>      yield object, criteria
>   end
>   filter('a', 'b') { |o,c| o != c }
> 
> or even a proc:
> 
>   def filter(object, op, criteria)
>      op.call(object, criteria)
>   end
>   filter('a', Proc.new{ |o,c| o != c }, 'b')

OK, some more pieces of puzzle :)

1. really, the former is used as bunch of filters:

Request.filter [ 
  [:base_type, :==, 'cpu'],
  [:fullname, :include?, 'Intel'],
  [:frequency, :>, 2300]
]

2. I'm planning inside Request to do the following:
a) search some pre-fetched array (through Array#select)
b) so some additional request to database

For (a), filter as lambda is good; but for (b), I need some format I can
convert into plain SQL.

Strange things, right? :)
 
> Sam

V.