Hello mailing list. This has already been posted on Usenet, sorry for the duplication. (The gateway seems to be one-way at the moment.)
Dave
···
-----
Hi,
My solution is available here:
http://www.dave.burt.id.au/ruby/roman_numerals.rb
It can be used as a library (it pollutes String and Integer 
or as
required from the command line, filtering integers to roman numeral strings
and vice-versa.
An outline:
# Contains methods to convert integers to roman numeral strings and
vice-versa.
module RomanNumerals
# Maps roman numeral digits to their integer values
DIGITS = {
# The largest integer representable as a roman numerable by this module
MAX = 3999
# Stolen from O'Reilly's Perl Cookbook 6.23. Regular Expression Grabbag
REGEXP = /^M*(D?C{0,3}|C[DM])(L?X{0,3}|X[LC])(V?I{0,3}|I[VX])$/i
# Maps some integers to their roman numeral values
@@digits_lookup = DIGITS.inject({
# Converts +int+ to a roman numeral
def self.from_integer(int)
# main loop:
@@digits_lookup.keys.sort.reverse.each do |digit_value|
while remainder >= digit_value
# Converts +roman_string+, a roman numeral, to an integer
def self.to_integer(roman_string)
# main loop:
roman_string.to_s.upcase.split(//).reverse.inject(0) do |memo, digit|
# Returns true iif +string+ is a roman numeral.
def self.is_roman_numeral?(string)
class String
# Considers string a roman numeral numeral,
# and converts it to the corresponding integer.
def to_i_roman
# Returns true iif the subject is a roman numeral.
def is_roman_numeral?
class Integer
# Converts this integer to a roman numeral.
def to_s_roman
# Processes ARGF as per Quiz requirement - converts numbers to roman
numerals and vice versa
if __FILE__ == $0
Cheers,
Dave
Thanks for copying it over here so I would see it, Dave. I went back and browsed the newsgroup and picked up Timothy Byrd's solution as well. That misbehaving gateway is hard on me. 
James Edward Gray II
···
On Mar 7, 2005, at 8:04 AM, Dave Burt wrote:
Hello mailing list. This has already been posted on Usenet, sorry for the duplication. (The gateway seems to be one-way at the moment.)
"James Edward Gray II" <james@grayproductions.net>:
Hello mailing list. This has already been posted on Usenet, sorry for the duplication. (The gateway seems to be one-way at the moment.)
Thanks for copying it over here so I would see it, Dave. I went back and browsed the newsgroup and picked up Timothy Byrd's solution as well. That misbehaving gateway is hard on me.
Me too... having to join a hundred-plus-messages-per-day mailing list that floods my mailbox just to submit my quiz solution... life's tough, isn't it?
Anyway, I have an update quiz-solution-wise.
I had a niggling feeling something was missing from my solution before I submitted. And everyone else's once I'd read them all. And here it is:
# Enables uppercase roman numerals to be used interchangeably with integers.
# They are auto-vivified RomanNumeral constants
# Synopsis:
# 4 + IV #=> VIII
# VIII + 7 #=> XV
# III ** III #=> XXVII
# VIII.divmod(III) #=> [II, II]
def Object.const_missing sym
raise NameError.new("uninitialized constant: #{sym}") unless RomanNumerals::REGEXP === sym.to_s
const_set(sym, RomanNumeral.get(sym))
end
Of course, this requires a RomanNumeral class, which acts like an Integer but looks like a... well, roman numeral.
Go and download http://www.dave.burt.id.au/ruby/roman_numerals.rb again!
Cheers,
Dave
That is a neat trick! Thanks a lot for sharing.
Regards,
Brian
···
On Tue, 8 Mar 2005 16:29:11 +0900, Dave Burt <dave@burt.id.au> wrote:
"James Edward Gray II" <james@grayproductions.net>:
>> Hello mailing list. This has already been posted on Usenet, sorry for the
>> duplication. (The gateway seems to be one-way at the moment.)
>
> Thanks for copying it over here so I would see it, Dave. I went back and
> browsed the newsgroup and picked up Timothy Byrd's solution as well. That
> misbehaving gateway is hard on me.
Me too... having to join a hundred-plus-messages-per-day mailing list that
floods my mailbox just to submit my quiz solution... life's tough, isn't it?
Anyway, I have an update quiz-solution-wise.
I had a niggling feeling something was missing from my solution before I
submitted. And everyone else's once I'd read them all. And here it is:
# Enables uppercase roman numerals to be used interchangeably with integers.
# They are auto-vivified RomanNumeral constants
# Synopsis:
# 4 + IV #=> VIII
# VIII + 7 #=> XV
# III ** III #=> XXVII
# VIII.divmod(III) #=> [II, II]
def Object.const_missing sym
raise NameError.new("uninitialized constant: #{sym}") unless
RomanNumerals::REGEXP === sym.to_s
const_set(sym, RomanNumeral.get(sym))
end
Of course, this requires a RomanNumeral class, which acts like an Integer but
looks like a... well, roman numeral.
Go and download http://www.dave.burt.id.au/ruby/roman_numerals.rb again!
Cheers,
Dave
--
Brian Schröder
http://ruby.brian-schroeder.de/
Dave Burt wrote:
Go and download http://www.dave.burt.id.au/ruby/roman_numerals.rb again!
Nice, now Ruby has them, too, like Perl did before. Small patch here:
--- roman_numerals.rb.1 Tue Mar 8 08:27:13 2005
+++ roman_numerals.rb Tue Mar 8 13:39:07 2005
@@ -135,7 +135,7 @@
else
to_i = value.to_s.to_i_roman
end
- @@all_roman_numerals[to_i] || RomanNumeral.new(to_i)
+ @@all_roman_numerals[to_i] || new(to_i)
end
def inspect
You can do funny things with those Roman numbers, BTW:
>> I += 1 ; I == II
(irb):1: warning: already initialized constant I
=> true
···
--
Florian Frank