Pragmas

[Lars T Hansen]

Pragmas are invariably lexically scoped.

Some pragmas are probably more useful at the top level, "use strict"
is among these.  One pattern we think might develop is  "use strict"
at the top level, followed by "use standard" inside some blocks where
strict mode gets in the way (if only temporarily during program
development).

--lars

On Nov 12, 2007 10:18 AM, Peter Hall <peter.hall at memorphic.com> wrote:
> What is the scope of a pragma such as that? Is it just the current
> lexical scope, like a "use namespace" statement, or does it change the
> behaviour for the entire program? If it's the latter, isn't there a
> compatibility problem between libraries? If it's the former, do you
> anticipate that es4 programs will be littered with "use strict"
> pragmas? Think Fortran and "implicit none"....
>
> I assume this has been previously discussed, but I couldn't find it,
> so apologies if that is the case.
>
> Peter
>
>
> On 11/12/07, Brendan Eich <brendan at mozilla.org> wrote:
> > On Nov 12, 2007, at 9:00 AM, Jonathan Watt wrote:
> >
> > > Hi,
> > >
> > > As I understand it the reason assignment to ReadOnly properties
> > > fails silently
> > > is that there was no try-catch prior to ECMAScript 3.
> >
> > Right. Netscape 2 reported a fatal error, but during ES1
> > standardization we agreed to go with silence is (golden|deadly).
> >
> > > Could/will edition 4 require an exception to be thrown in strict mode?
> >
> > Overtly incompatible, also highly desirable. So opt-in versioning
> > could enable this, but it's one more migration headache (see recent
> > exchange between Mark Miller and myself). An alternative would be a
> > pragma of some sort:
> >
> >    use readonly error
> >
> > or perhaps
> >
> >    use readonly throw
> >
> > We try to make pragmas more readable, sometimes with an extra word;
> > not sure this is the best way to phrase it still, but the idea would
> > be to enable throwing of a ReadOnlyError on assignment to a ReadOnly
> > property. Comments?
> >
> > /be
> >
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> >
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