ES6 and Error Object properties

[Kevin Curtis]

Re alt-JS languages and getting line's number from runtime errors -

I'm experimenting with an ECMAScript AST serialization format in
JsonML - based on the output from the V8 --print_json_ast shell flag.
Line numbers can be passed through as attributes. eg

var ast_str =  '["IfStatement", {line:44}, ["CompareOperation",
{"op":"GT",}, ...";
JSON.AST.execute(ast_str);
-> runtime error line number printed as was explicitly set on the AST node

alt-JS languages/DSL's could target this JsonML format.


On Wed, Nov 4, 2009 at 8:11 PM, Patrick Mueller <pmuellr at yahoo.com> wrote:
> Coincidently (!!!), I recently opened a feature request in WebKit on this
> topic, kind of:
>
>        https://bugs.webkit.org/show_bug.cgi?id=30933
>
> Not sure I'll have time to do anything about it, and surely won't without
> some kind of real framework helping out to add support on their end ...
>
> BTW, I thought JavaScript was the new assembler, not the new C.
>
> On Nov 4, 2009, at 3:04 PM, P T Withington wrote:
>
>> Sure would be nifty to have #file and #line directives, now that
>> Javascript is the new C.
>>
>> FWIW, OpenLaszlo generates annotations like so:
>>
>> Filename, line, column:
>>
>> /* -*- file: lpp-8534.lzx#10.7 -*- */
>>
>> Same file, but line numbering needs to be reset (because output has more
>> or less lines corresponding to source):
>>
>> /* -*- file: #15 -*- */
>>
>> No corresponding source file (i.e., generated code follows):
>>
>> /* -*- file: -*- */
>>
>> I can see merits to one gigantic comment up front with a mapping table ala
>> Caja, but we found interspersing them worked better for humans staring at
>> Javascript "assembly" in a Javascript debugger.
>>
>> IWBNI @sourceurl could be expanded in some form to work with loaded
>> files...
>>
>> On 2009-11-04, at 14:39, Patrick Mueller wrote:
>>
>>> Coincidently, I posted a blog entry on SyntaxError and eval() yesterday:
>>>
>>>        http://pmuellr.blogspot.com/2009/11/evil-eval.html
>>>
>>> On Nov 4, 2009, at 11:10 AM, Kevin Curtis wrote:
>>>
>>>> This has probably been chewed over but -
>>>>
>>>> The ES5 spec defines 'name' and 'message' as properties of the Error -
>>>> and ReferenceError, SyntaxError etc - objects.
>>>>
>>>> Currently engines have useful additional non-standard properties:
>>>> Mozilla - fileName, lineNumber and stack.
>>>> V8 - stack (and type, arguments). (The string returned by 'stack' is
>>>> not in the same format as Mozilla).
>>>> JSC - line, sourceId, sourceURL, expressionBeginOffset,
>>>> expressionCaretOffset ,expressionEndOffset - and a few others for
>>>> Statement errors.
>>>>
>>>>
>>>> Any chance for ES6 on standardizing Error object property/ies which
>>>> report back the error location.
>>>>
>>>> Maybe a property 'location' on the Error object which returns an object.
>>>> e.g
>>>> e.location ->
>>>> {fileName:<filename>, pos: <character posNumber>, line:<lineNumber> ,
>>>> lineEnd:<lineNumber>, col:<colNumber> , colEnd:<colNumber>, stack:
>>>> <stackString>}
>>>>
>>>> With maybe pos and line being mandatory properties and the other
>>>> properties set if they can be set.
>>>>
>>>
>>
>
> Patrick Mueller - http://muellerware.org/
>
>
>
>
>