From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2007-11-22T19:33:08+09:00
Subject: Re: read, write, seek method in a ring buffer class

On Nov 22, 2007 9:59 AM, Martin Durai <martin@angleritech.com> wrote:
> Actually i need to create a ring buffer class, with read, write, seek
> methods.
>
> Read should take number as an argument(number of bytes to read) and
> should return a string. when you read, you need to read either the
> request number of bytes or the availlable number of bytes, whichever is
> smaller. when you read you advance forward the read_position.
>
> similarly write method should take string as a argument. now advance
> forward the write position.
>
> seek should take number as a argument and return nothing. it should do
> range checking. seek changes the read position.

I think you are doing too much work. I would wrap a StringIO which is basically
what you want:
$ cat ringbuffer.rb && ruby ringbuffer.rb
require 'stringio'

class RingBuffer
        def initialize string = ""
                @string_io = StringIO.new string
        end

        def read bytes = nil
                @string_io.read bytes
        end

        def write string
                cur_pos = @string_io.pos
                @string_io.seek(0, IO::SEEK_END)
                @string_io.write string
                @string_io.seek(cur_pos, IO::SEEK_SET)
                string.length
        end

        def seek bytes
                @string_io.seek bytes
        end
end

b = RingBuffer.new
b.write "abcde"
puts b.read
b.write "fghij"
puts b.read(2)
puts b.read(1)
b.write "12345"
puts b.read(5)


abcde
fg
h
ij123

Of course you might need to add some checks to fulfill your error
handling requirements but this might get you started.

Jesus.