From: Russ Pridemore <russ.pridemore@...>
Date: 2006-08-16T06:34:11+09:00
Subject: Re: problem with date.succ

> Russ Pridemore schrieb:
>> I'm having difficulty with a small program I'm writing dealing with
>> dates.  I've written the calendar class below.  It works just fine
>> when calling getMonth for all months EXCEPT NOVEMBER.  Interrupting
>> the call while in irb shows that it is busy in the reduce method of
>> Rational, called from Date.  Any ideas?
>>
>> (...)
>>
>>   def getMonth(mo)
>>      dt = Date.new(@year, mo, 1)
>>      i = dt.month
>>      list = Array.new
>>      while i != (mo+1) % 12
>>         wk = getWeek(dt.month, dt.day)
>>         dt = wk[6].succ
>>         i = dt.month
>>         list.push(wk)
>>      end
>>      list
>>   end
>>
>> (...)
>
> Russ, for November, "mo" is 11, and "(mo+1) % 12" is zero, but
> "dt.month" and "i" are always in the range (1..12), so you've got an
> endless loop. Replace the line
>
>    while i != (mo+1) % 12
>
> with
>
>    next_month = mo % 12 + 1
>    while i != next_month
>
> and at least the loop should work as you expect.
>
> Regards,
> Pit
>

Pit,
Thank-you very much.  Can't believe I didn't see that mistake.

Any idea why ruby's date class needs to use rational numbers, though?
Every time I'd get into the loop and break out in irb, I'd see a stack
trace pointing to rational.rb...

Russ