From: MonkeeSage <MonkeeSage@...>
Date: 2007-11-30T15:10:03+09:00
Subject: Re: hash.clear("value")

On Nov 29, 4:35 am, Robert Klemme <shortcut...@googlemail.com> wrote:
> 2007/11/28, MonkeeSage <MonkeeS...@gmail.com>:
>
>
>
> > On Nov 28, 1:47 pm, Andrew Stone <stoneli...@gmail.com> wrote:
> > > Note:  parts of this message were removed by the gateway to make it a legal Usenet post.
>
> > > Hello all,
>
> > > Was just wondering if there was something simple like:
>
> > > hash.clear("value")
>
> > > This would remove all entries from the hash whose value == "value".
>
> > > Yeah, I know about delete_if, this would just be more succinct.  I can be
> > > lazy sometimes.
>
> > > thanks,
> > > andy
>
> > > --
> > > Andrew Stone
>
> > You can always wrap delete_if...
>
> > class Hash
> >   def remove(target)
> >     self.delete_if { | key, value |
> >       value == target
> >     }
> >   end
> > end
>
> Just a subtle point: IMHO it is better to put "target" on the left
> side of the comparison because that gives the caller more control on
> the deletion criterion:
>
> class Hash
>  def remove(target)
>    delete_if { | key, value |
>      target == value
>    }
>  end
> end
>
> For example, you could do
>
> crit = Object.new
> def crit.==(x) x < 10 end
> a_hash.remove crit # remove all entries where value is < 10

Nice. :)

> It's a similar pattern to how "case" does comparison via "===".  But
> then again, this is probably even better:
>
> class Hash
>   def remove_val
>     delete_if {|k,v| yield v}
>     self
>   end
> end
>
> Because it's more modular.  But then again, you can use delete_if directly. :-)

Yes, but we're lazy! ;) No blocks here! Heh. Otherwise we would just
use delete_if! ;)

> Kind regards
>
> robert
>
> --
> use.inject do |as, often| as.you_can - without end