From: Caleb Clausen <vikkous@...>
Date: 2006-03-03T04:18:17+09:00
Subject: Re: Subclassing Struct.new

On 3/1/06, Yukihiro Matsumoto <matz@ruby-lang.org> wrote:
> My original intention is _not_ to use local variables before their
> first assignment, but to extent their scope to by their outer most
> appearance in the method.

I'm trying to understand the distinction... I think I see. It's
cases where the assignment happens (or might happen?) after
a use at runtime, but also, the use comes before the assignment
in the lexical order.

> But at the same time, I expect the new rule
> to solve
>
>    print foo if foo = bar()

The perfect example. This, I agree ought to work as expected. I'm
not sure I can see an easy way to make it work, but it seems like
there might be a special case... on the other hand, maybe just
a special case isn't good enough. What about this:

until foo && foo.k
  foo=readfoo
end

Sort of silly, there's a better way to do this. But the question is, do
you want foo to be a variable on the first line? And this case:

> | def baz
> |   n # will be variable
> |   n = 3
> |   n # variable
> | end

is clearly always use before definition. Should this cause a warning or
something then?

> I will ponder the new rule (and implementation) bit more.

One thought I had: if there isn't a clever trick for inline if, maybe the
best way is to keep the existing semantics and issue a warning if
there's a method call with a name that subsequently is used for a
local variable in the same scope. That shouldn't be too hard.