Pragmas

[Jeff Dyer]

Got it. Thanks!

Jd


On 11/12/07 10:25 AM, Peter Hall wrote:

> Also, there is a minor bug [1] with the pragma syntax:
> 
> Pragma :
> UsePragma  SemicolonFull
> ImportPragma  SemicolonFull
> 
> UsePragma :
> use  PragmaItems  SemicolonFull
> 
> 
> resulting in two semicolons being required after a "use" pragma.
> 
> 
> Peter
> 
> 
> [1] http://wiki.ecmascript.org/doku.php?id=proposals:syntax_for_pragmas
> 
> 
> 
> 
> 
> On 11/12/07, 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
>>> 
>>> _______________________________________________
>>> Es4-discuss mailing list
>>> Es4-discuss at mozilla.org
>>> https://mail.mozilla.org/listinfo/es4-discuss
>>> 
>> 
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