From: Robert Klemme <bob.news@...>
Date: 2004-05-05T01:48:56+09:00
Subject: Re: model for my problem (network simulator)


"Gergely Kontra" <kgergely@mcl.hu> schrieb im Newsbeitrag
news:20040504125533.GB27180@mlabdial.hit.bme.hu...
> On 0504, Robert Klemme wrote:
> > Nope, that's not the same:
> > irb(main):001:0> h=Hash.new {[]}
> > irb(main):002:0> h[1]
> > irb(main):003:0> h
> > => {}
> > irb(main):004:0> h=Hash.new {|h,k| h[k]=[]}
> > irb(main):005:0> h[1]
> > irb(main):006:0> h
> > => {1=>[]}
> > Your solution makes the idiom "h[key] << something" unusable since all
> > those arrays never make it into the hash.
>
> Oh, yes, I run into the problem, and this is the weird case, where
> h[key] << something and h[key] <<= something is different...

Note also that h[key] << something is more efficient since it does only one
hash lookup and no hash update.

Regards

    robert