From: Robert Klemme <shortcutter@...>
Date: 2011-08-31T23:56:58+09:00
Subject: Re: Prepend a character to a string in ruby

On Wed, Aug 31, 2011 at 4:46 PM, Gavin Kistner <phrogz@me.com> wrote:
> On Aug 31, 2011, at 08:29 AM, Hassan Schroeder <hassan.schroeder@gmail.com>
> wrote:
>
> On Wed, Aug 31, 2011 at 7:19 AM, Michal Suchanek <hramrach@centrum.cz>
> wrote:
>
>> It is sad there is no obvious method for that.
>
> But if it makes you happy, there can be :-)
>
> ruby-1.8.7-p352 > class String
> ruby-1.8.7-p352 ?> def >>(arg)
> ruby-1.8.7-p352 ?> self.insert(0, arg)
> ruby-1.8.7-p352 ?> end
> ruby-1.8.7-p352 ?> end
> => nil
> ruby-1.8.7-p352 > string = "bar"
> => "bar"
> ruby-1.8.7-p352 > string >> "foo"
> => "foobar"
> ruby-1.8.7-p352 >
>
>
> Since we're monkeypatching and mutating anyway, I like reversing the order
> so that the order of the arguments is the same as in the result:
> irb(main):001:0> class String
> irb(main):002:1> def >>(other)
> irb(main):003:2> other.insert(0,self)
> irb(main):004:2> end
> irb(main):005:1> end
> => nil
> irb(main):006:0> str = "bar"
> => "bar"
> irb(main):007:0> "foo" >> str
> => "foobar"

That triggered another idea:

irb(main):001:0> class String
irb(main):002:1>   def head=(s)
irb(main):003:2>     insert 0, s
irb(main):004:2>   end
irb(main):005:1>   def tail=(s)
irb(main):006:2>     self << s
irb(main):007:2>   end
irb(main):008:1> end
=> nil
irb(main):009:0> s = "foo"
=> "foo"
irb(main):010:0> s.head = "begin("
=> "begin("
irb(main):011:0> s
=> "begin(foo"
irb(main):012:0> s.tail = ")end"
=> ")end"
irb(main):013:0> s
=> "begin(foo)end"

Note the absence of readers.  Reasoning about why left as exercise for
the reader. :-)

Kind regards

robert

-- 
remember.guy do |as, often| as.you_can - without end
http://blog.rubybestpractices.com/