RE: [wsbpel] local variables overriding enclosing scope

["Satish Thatte" <satisht@microsoft.com>]

I don't recall how this rule came to be but I think Ugo has the probable explanation -- you can treat name+type as a unique differentiator as opposed to just name.  A kind of overloading.  While I am not entirely sure, I expect we just didn't want to get into that conundrum.  But this is one of those esoteric corners where the "right answer" is a matter of taste.  I would really prefer to disallow name duplication altogether but that's just me .. ;-)

________________________________

From: Yuzo Fujishima [mailto:fujishima@bc.jp.nec.com]
Sent: Wed 3/3/2004 5:39 PM
To: Ugo Corda; Danny van der Rijn; wsbpel@lists.oasis-open.org
Subject: Re: [wsbpel] local variables overriding enclosing scope



I think an inner-scope variable must override any outer-scope
variables of the same name regardless of their type.
I believe most, if not all, developers expect that semantics
because I don't know any scope-aware languages that don't
use the semantics.

Yuzo Fujishima
NEC Corporation

----- Original Message -----
From: "Ugo Corda" <UCorda@SeeBeyond.com>
To: "Danny van der Rijn" <dannyv@tibco.com>; <wsbpel@lists.oasis-open.org>
Sent: Thursday, March 04, 2004 9:23 AM
Subject: RE: [wsbpel] local variables overriding enclosing scope


I was just trying to expose the naming and visibility rules that seem to
be behind the 9.2 statement.

But you seem to be arguing with those rules, more than with the
statement itself. Well, I guess we are defining the language and we are
free to define our naming and visibility rules the way we want, as long
as they are reasonable and helpful when using the language. In
particular, it is up to us to determine what type of declaration can
hide others. Evidently the criteria for hiding must be related to how
much we consider the declarations to be "the same". Variable name is
clearly a way to define their sameness, but type could be an additional
criterion.

I personally don't have any strong feeling one way or another. Maybe the
original author can provide some use cases to illustrate the merits of
their choice.

Ugo

> -----Original Message-----
> From: Danny van der Rijn [mailto:dannyv@tibco.com]
> Sent: Wednesday, March 03, 2004 4:10 PM
> To: wsbpel@lists.oasis-open.org
> Subject: Re: [wsbpel] local variables overriding enclosing scope
>
>
> this appears to be a circular argument.
>
> "It is not permitted to have variables with same name but
> different messageType/type/element within an enclosing scope
> hierarchy..." "...because an innermost declaration cannot
> hide outer declarations having different messageType/type/element"
>
> the inner variable name unambiguously hides the outer one.
> why should its messageType/type/element matter?
>
> ----- Original Message -----
> From: "Ugo Corda" <UCorda@SeeBeyond.com>
> To: "Danny van der Rijn" <dannyv@tibco.com>;
> <wsbpel@lists.oasis-open.org>
> Sent: Wednesday, March 03, 2004 4:02 PM
> Subject: RE: [wsbpel] local variables overriding enclosing scope
>
>
> I would imagine that the rationale is the following:
>
> - in the case a variable is referenced in a scope, when
> multiple declarations of the same variable with same
> messageType/type/element exist in the enclosing scope
> hierarchy, the reference is unambiguous because the innermost
> declaration hides any outer declarations (it's as if there
> was only one declaration and all the others were hidden).
>
> - in the case a variable is referenced in a scope, when
> multiple declarations of the same variable with different
> messageType/type/element exist in the enclosing scope
> hierarchy, the reference is ambiguous because an innermost
> declaration cannot hide outer declarations having different
> messageType/type/element, and it is then unclear which
> declaration the variable reference is referring to.
>
> Ugo
>
>
> > -----Original Message-----
> > From: Danny van der Rijn [mailto:dannyv@tibco.com]
> > Sent: Wednesday, March 03, 2004 3:31 PM
> > To: wsbpel@lists.oasis-open.org
> > Subject: [wsbpel] local variables overriding enclosing scope
> >
> >
> > in 9.2, it says: "It is not permitted to have variables
> with same name
> > but different messageType/type/element within an enclosing scope
> > hierarchy."
> >
> > can someone explain to me why it is necessary to have this
> > restriction?
> >
> >
> > To unsubscribe from this mailing list (and be removed from
> the roster
> > of the OASIS TC), go to
> > http://www.oasis-open.org/apps/org/workgroup/wsbpel/members/le
> ave_workgroup.php.
>
>
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