From: Brian Candler <lists@...>
Date: 2012-10-31T22:55:45+09:00
Subject: Re: bug?: local variable created in if modifier not available in modified expression

Mean L. wrote in post #1082116:
> Ruby parses left to right, so it see "lo" on the assignment side of the
> if. Since no local variable "lo" has been encountered yet it must be a
> method. Ruby then encounters the assignment to lo and creates the local
> variable.
> _____________________________________
>
> I can't say this makes sense to me.  Ruby otherwise is a dynamic
> language, but with respect to local vars it's suddenly static, and the
> parser wants to identify all local vars in one left to right parse pass,
> before the code is run.

Two important reasons:

1. It would be enormously inefficient if every time you invoked an 
expression like 'a' you had to decide at run-time whether it was a 
variable or a method call

2. It is much easier to inspect a piece of code and be able to say with 
certainty at any point whether 'a' is a variable or method call. (This 
is also a good reason why class and def start new scopes; you never need 
to look outside of the current method to resolve the variable/method 
ambiguity)

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