From: corey konrad <0011@...>
Date: 2006-05-16T09:27:21+09:00
Subject: Re: learn to program

oh ok he is just talking about variable scope it was kind of hard to 
tell from his example for some resaon, i dont know i think i am going to 
skip this learn to program book, this chris guy really doesnt know how 
to explain things to a person with a beginner mind set. i also am having 
problems running his code examples i really dont  understand how the 
code below works but when i copy and paste it into the live ruby program 
all it does is close the live ruby program and shuts it down.

def ask question
good_answer = false
while (not good_answer)
puts question
reply = gets.chomp.downcase
if (reply == ' yes' or reply == ' no' )
good_answer = true
if reply == ' yes'
answer = true
else
answer = false
end
else
puts ' Please answer "yes" or "no".'
end
end
answer # This is what we return (true or false).
end





Natevw wrote:
> corey konrad wrote:
>> puts tough_var
>> tough_var to the other (via the method call, the only way they can even
>> sort of communicate) so that both were pointing to the same string.
>> Then little_pest pointed its own local tough_var to nil, but that
>> did nothing to the tough_var variable outside the method.
>> 
> 
> Looks like he's trying to get at the "scope" of variables.
> 
> I think that his example might be more clearly written with parentheses:
> 
> [code]
> 1: def little_pest(tough_var)
> 2:  tough_var = nil
> 3:  puts ' HAHA! I ruined your variable!'
> 4: end
> 5:
> 6: tough_var = ' You can\' t even touch my variable!'
> 7: little_pest(tough_var)
> 8: puts tough_var
> [/code]
> 
> Pay attention to 'tough_var' through the code, it actually refers to two
> different variables:
> 1) in line 1, 'tough_var' is the name given to the one argument (~=input
> value) that the little_pest function takes. It is a local variable.
>    in line 2, this local variable is set to nil.
> 
> 2) in line 6, a global variable named 'tough_var' is declared and set to
> the "You can't touch..." line
>     in line 7, little_pest is called with the value of the global 
> tough_var
> 
> 
> So when tough_var is set to nil in line 2, all that is being set to nil
> is the local variable named 'tough_var', not the variable from lines 
> 6-8.
> 
> 
> To the Ruby interpretter, the code might as well be written as:
> 
> 1: def little_pest(var1)
> 2:  var1 = nil
> 3:  puts ' HAHA! I ruined your variable!'
> 4: end
> 5:
> 6: var2 = ' You can\' t even touch my variable!'
> 7: little_pest(var2)
> 8: puts var2
> 
> 
> 
> HTH...I'm just learning Ruby, so maybe somebody could correct the
> details (passing by value,etc.)....but that's what the author is getting 
> at.
> 
> 
> 
> -natevw


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