From: Gerr <gerald@...>
Date: 2006-07-17T21:45:11+09:00
Subject: First ruby code, need hint on iterator


Hello,

Consider the following code which generates a hexdump of a string:

----------------------------------------------------------------------

#!/usr/bin/ruby

module Dump

        def hexdump

                x = 0
                offset = 0
                hex = ""
                str = ""
                out = ""

                each_byte { |c|
                        
                        x = x + 1

                        hex << sprintf("%02x ", c)
                        hex << "- " if(x == 8)         
                        str << ((c >= 32 && c<=127) ? c.to_i.chr : ".")

                        if(x == 16)
                                out << sprintf("%08x: %-50s %s\n", offset, hex, str)
                                x = 0
                                hex = ""
                                str = ""
                                offset = offset + 16
                        end
                }

                out << "\n"

                return out
        end
end     


l = $stdin.read(10000)
l.extend Dump
print l.hexdump

----------------------------------------------------------------------

This program has a serious flaw: only if 16 bytes are collected from the input,
a new line with hex codes is printed. If the input string has a length that is
not a multiple of 16, the remaining bytes will not be handled.

A solution would be to duplicate the line

	out << sprintf("%08x: %-50s %s\n", offset, hex, str)

somewhere at the end of the loop, so that any remaining buffers are printed.
This forces me to duplicate code, though, which is not what I want.

The obvious solution for me would be to change the line

	if(x == 16) 

to something like

	if((x == 16) || (c.is_the_last_element_from_the_set))


The problem is in the fictional thingy 'is_the_last_element_from_the set',
which I believe is not available. 

What would be the idiomatic solution for this in Ruby ? Any other comments on
the code are welcome as well, ofcourse

Thank you