From: Gary Wright <gwtmp01@...>
Date: 2007-09-19T04:07:28+09:00
Subject: Re: Variable / Method Ambiguity


On Sep 17, 2007, at 12:08 PM, Jeffrey 'jf' Lim wrote:

> On 9/17/07, David A. Black <dblack@rubypal.com> wrote:
>> Hi --
>>
>> On Mon, 17 Sep 2007, Summercool Summercool wrote:
>>
>> <snip>
>>>
>>> (as described in the PickAx2 book, p. 329)
>>>
>>> So at first I thought a Ruby program is interpreted?  If  
>>> interpreted,
>>> then the interpreter will see the "a = 1" at first as treat "a" as a
>>> variable, and then the second time it sees "a", the interpreter  
>>> should
>>> treat it as a variable again, not as a method.
>>
>> No, because there's no such variable in scope. The second time  
>> through
>> the loop, there's no assignment to a, and the first variable a has
>> gone out of scope.
>
> so this is lexical scoping, then?

No, it is just that Ruby has a single-pass parser.  The parser needs
to decide if an identifier is a local variable or a zero-argument method
before it has seen the entire text of the file (no look-ahead).  Until
the parser sees an assignment of the form "a = ..." it assumes
that 'a' is a method call.

So if/then/else statements do *not* create new lexical scopes.


Gary Wright