From: John Merlino <stoicism1@...>
Date: 2010-01-18T02:58:05+09:00
Subject: Re: What does ||= represent in this situation?

John Merlino wrote:
> John Merlino wrote:
>> Hey all, || is equal to Or. So what would ||= in this situation?
>> 
>> def expensive
>>   @expensive ||=
>>     begin
>>       n = 99
>>       buf = ""
>>       begin
>>         buf << "#{n} bottles of beer on the wall\n"
>>         # ...
>>         n -= 1
>>       end while n > 0
>>       buf << "no more bottles of beer"
>>     end
>> end
>> 
>> Thanks for all suggestions. Also if you can interpret this, that would
>> be nice. What it appears here is an attempt of a do while loop.
> 
> I can't figure out how to edit a post. But I don't need anyone to 
> interpret the code from "begin" to "end". I know this is executing n 
> until it is no longer greater than 0. But what I'm trying to find is 
> something similar to what can be done in javascript:
> 
> In javascript, there are  cases where you have a variable called, let's 
> say, old which contains 50 positions in an array. Now you want each 
> position of the array to be unique. But at the same time, you want to 
> generate random numbers for each item of the array:
> 
> var old = new array(20)
> var new
> do {
>   new = Math.floor(Math.random()*100) + 1;
> }
> while (old[new]);
> 
> old[new] = true;
> 
> Is there a way to do a do while loop like this in Ruby?

Something like this?

def unique_num
 @unique_num ||=
  begin
   old = [75] #The old variable holds 75 indexes of an array.
   new = math.floor(math.random) * 100 + 1 #The new variable yields a 
random number from 1 to 100.
   begin
    old << new #We append the random number into the array.
   end while old[new] #We loop again if the number already exists, until 
we get another number in the position.
   old[new] = true #We set it to true since the number is now in the 
array.
  end

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