From: Jamis Buck <jgb3@...>
Date: 2004-02-05T06:25:25+09:00
Subject: Re: flip flop operator proposal (from condition to condition do )

nobu.nokada@softhome.net wrote:

>Hi,
>
>At Wed, 4 Feb 2004 15:23:10 +0900,
>Jamis Buck wrote in [ruby-talk:91521]:
>  
>
>>In general, you want a parser that extracts everything between BEGIN and 
>>END, but there are a few cases where you want to treat the word 
>>'special' as the end instead, and then ignore everything until the next 
>>BEGIN.
>>
>>while line = file.gets
>>  if in line=~/BEGIN/ .. line=~/END/ => state
>>    state.set_state( line =~ /special/ )
>>    if state.get_state
>>      # process line
>>    end
>>  end
>>end
>>    
>>
>
>Will set_state turn the state true, or false?  Seeing the next
>line, set_state(true) makes get_state to return false...
>
>  
>

Well, what I had envisioned was the following:

  FlipFlip#get_state: return the current truth value of the flip flop.
  FlipFlop#set_state( state ): set the truth value of the flip flop

And you're right -- there's a typo in my example. :(  The set_state call 
should be:

  state.set_state( line !~ /special/ )

>>Like I said, it's pretty contrived, and would be better solved by 
>>choosing smarter guard conditions. However, it demonstrates a situation 
>>where exposing an interface for manipulating a flip-flop's state may be 
>>useful.
>>    
>>
>
>Rather, what about binding a flip-flop operator to a local
>variable?
>  
>

Fascinating concept--that would certainly be simpler.  The only benefit 
I can see to using an object as opposed to a local variable binding is 
that you could pass the flipflop object into a method and have any 
manipulations made on it in the method be effective outside the method.

-- 
Jamis Buck
jgb3@email.byu.edu

ruby -h | ruby -e 'a=[];readlines.join.scan(/-(.)\[e|Kk(\S*)|le.l(..)e|#!(\S*)/) {|r| a << r.compact.first };puts "\n>#{a.join(%q/ /)}<\n\n"'