From: Corey Konrad <0011@...>
Date: 2007-03-16T09:57:43+09:00
Subject: Re: to_a

Alex Gutteridge wrote:
> On 16 Mar 2007, at 09:33, Corey Konrad wrote:
> 
>>> The issue isn't with the parentheses, but with the behavior of the
>>>
>> language but it seems pretty difficult.
>>
>> -- 
>> Posted via http://www.ruby-forum.com/.
>>
> 
> I think you understand fine, just take your time and take each step
> in turn. As you say, the code below works:
> 
> array = (1..8).to_a
> puts array[1]
> 
> This makes a Range object from '(1..8)' and converts it to an Array
> using '.to_a'. This array is assigned to the variable 'array' and you
> can access it as normal.
> 
> The code below doesn't work:
> 
> array = 1..8
> array.to_a
> puts array[1]
> 
> This makes a Range object from '1..8' and assigns it to 'array'. You
> then create a new Array using 'array.to_a' but do not assign it to
> anything ('array' is still a Range). This means the final statement
> doesn't work.
> 
>  From your second post it looks like you tried:
> 
> array = 1..8.to_a
> puts array[1]
> 
> This doesn't work because you are asking for a Range constructed from
> '1' to '8.to_a'. I.e a Range from the Integer 1 to the Array '[8]'.
> This is an invalid Range. The parentheses in the first example ensure
> that the Range is constructed first and then the '.to_a' method is
> called on that. Essentially the method call '.to_a' takes precedence
> over the Range operator '..'.
> 
> Hope that helps.
> 
> Alex Gutteridge
> 
> Bioinformatics Center
> Kyoto University

ok, yeah now i understand why the () are there i just didnt see that for 
some reason.

See when i tried

> array = 1..8
> array.to_a
> puts array[1]

my view was that i was creating a range and assigning it to array and 
then taking that range in array and converting it to an array by using 
array.to_a. I had no idea i was just creating a new array there is no 
way to tell that from looking at it for me even now, to me that code 
looks like i am transforming the range stored in array... into an array. 
My view was that array.to_a meant, take the range stored in array and 
convert it to an array but that isnt what its doing its just converting 
the variable array into an empty array? I dont know i still feel like i 
am missing something that is going on behind the scenes, learning ruby 
as a first programming language kind of seems like learning short hand 
english first instead of becoming fluent in english grammer.



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