From: Mayank Kohaley <mayank.kohaley@...>
Date: 2011-12-09T19:22:25+09:00
Subject: Re: How can I do h["foo"] += "bar" if h["foo"] does not exist?

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On Fri, Dec 9, 2011 at 2:53 PM, Robert Klemme <shortcutter@googlemail.com>wrote:

> On Fri, Dec 9, 2011 at 8:38 AM, Ryan Davis <ryand-ruby@zenspider.com>
> wrote:
> >
> >
> > On Dec 8, 2011, at 23:06, Mayank Kohaley <mayank.kohaley@gmail.com>
> wrote:
> >
> >> You can have something like this to check whether the key is present or
> >> not-
> >>
> >> h["key"] += value if h["key"]
> >
> > Values can be false/nil.
>
> Also, this is inelegant.  Either do this to prevent accidental
> modification of the default object:
>
> irb(main):006:0> h = Hash.new("".freeze)
> => {}
> irb(main):007:0> h[:e] += "foo"
> => "foo"
> irb(main):008:0> h[:f] += "bar"
> => "bar"
> irb(main):009:0> h
> => {:e=>"foo", :f=>"bar"}
> irb(main):010:0> h[:f] += "foo"
> => "barfoo"
> irb(main):011:0> h
> => {:e=>"foo", :f=>"barfoo"}
>
> Or, what I'd consider better because it is more efficient, use
> String#<< to append and not create new instances all the time:
>
> irb(main):012:0> h = Hash.new {|ha,k| h[k] = ""}
> => {}
> irb(main):013:0> h[:e] << "foo"
> => "foo"
> irb(main):014:0> h[:f] << "bar"
> => "bar"
> irb(main):015:0> h
> => {:e=>"foo", :f=>"bar"}
> irb(main):016:0> h[:f] << "foo"
> => "barfoo"
>
> Kind regards
>
> robert
>
>
> --
> remember.guy do |as, often| as.you_can - without end
> http://blog.rubybestpractices.com/
>
>

Thanks for the enlightenment!!! Learned something about hashes today. :)

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