From: matt@... (matt neuburg)
Date: 2008-01-26T11:44:56+09:00
Subject: Re: why must I initialize this variable?

7stud -- <bbxx789_05ss@yahoo.com> wrote:

> Gary Wright wrote:
> > Execution isn't moving backwards.  You have to think of it as a two
> > step process, parsing then execution.  The parser is going to prepare:
> > 
> >   puts "#{hi}" if (hi = "hello")
> >          puts hi
> > 
> > is such a way that the execution step sees:
> > 
> >         if (hi = "hello")
> >            puts "#{hi}"
> >         end
> >         puts hi
> > 
> > So during execution, nothing is going backwards.  But the parser has
> > already tagged various parts of the code such that the 'hi' token in
> > the conditional is an local variable assignment from a literal (thus
> > the warning), the 'hi' token in the then clause as a method call, and
> > the 'hi' token on the final puts as a local variable.
> > 
> > These three issues
> > 1) 0-argument method calls and local variables
> >     are syntactically identical
> > 2) local variables don't have to be declared.
> > 3) Ruby's if/unless modifiers imply execution
> >     order that is backwards from textual order
> > 
> 
> Thanks for the detailed explanation.  :)
> 
> > Another corner case is
> 
> Yep, I already know about that one.

Thanks to all who contributed to this explanation - it's exactly what I
wanted to know. m.


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