Hmmm, can't find your proposal, mind to share the link directly? I did however find a comment from Brendan Eich 3 years ago that basically resonated with my idea that refutable patterns and matching is the way to go for conditional catch, and another thread from a year ago that this still is the generally accepted consensus on the topic.
https://esdiscuss.org/topic/conditional-catch-clause https://esdiscuss.org/topic/conditional-catch So I guess this is just yet another highly requested feature that somehow ended up in a deadlock then got buried into the deep... On Tuesday, May 17, 2016, Isiah Meadows <[email protected]> wrote: > Pattern matching has been considered before, and the performance will suck > if you consider things like `Point(x, y)`. It's very hard to optimize at > runtime, and engines don't have time to optimize that statically. > > If you want to consider Clojure as an example of one that does this > dynamically, it still works ahead of time. The inheritance chain is known > statically, and Clojure uses immutable ADTs primarily, so it can do this > very quickly. > > (Spoiler alert: I've tried proposing this myself. It didn't work. You can > find previous talk by searching esdiscuss.com via Google.) > > On Sat, May 14, 2016, 12:17 G. Kay Lee < > [email protected] > <javascript:_e(%7B%7D,'cvml','balancetraveller%[email protected]');>> > wrote: > >> This is another really far shot - but I'd rather suggest that we should >> redefine the role of `case` so that it's no longer just a part of the >> `switch` statement but something more generic, as well as introducing a >> `match` keyword to enable pattern matching, including the power of matching >> by type, so that we can achieve the desired effect in a way illustrated in >> the snippets below: >> >> ``` >> // plain old switch-case >> >> switch (expression) { >> case value1: >> case value2: >> ... >> break; >> >> default: >> ... >> } >> >> // switch-case with pattern matching; pattern-match by type in this >> example >> >> switch (expression) match { >> case _: boolean >> ... >> break; >> >> default: >> ... >> } >> >> // try-catch with pattern matching >> >> try { >> ... >> } catch (error) match { >> case _: TypeError >> case _: SyntaxError >> ... >> break; >> >> default: >> ... >> } >> ``` >> >> Just some rough idea; inspired by Scala syntax. >> >> >> >> On Sat, May 14, 2016 at 1:49 AM, Joseph Groseclose <[email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: >> >>> I offered a few syntaxes for this, perhaps the bitwise OR "|" would be >>> better. >>> >>> On Fri, May 13, 2016 at 1:33 PM, Michał Wadas <[email protected] >>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: >>> >>>> > } catch (await FCL.load(...), await FCL.load(...)) (e) { >>>> Then you have to override comma operator ( >>>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Comma_Operator >>>> ) in one specific context... >>>> >>>> On Fri, May 13, 2016 at 7:14 PM, Joe Groseclose <[email protected] >>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: >>>> >>>>> @JoePea, that is one of the syntaxes I recommend in the proposal. >>>>> >>>>> @michalwadas The primary goal of this I think is to create a standard >>>>> feature, but I do not see why an expression wrapped in parenthesis >>>>> ultimately resulting in an error class would not be supported. >>>>> >>>>> Example: >>>>> >>>>> ... >>>>> >>>>> } catch (await FCL.load(...), await FCL.load(...)) (e) { >>>>> ... >>>>> >>>>> Or something similar for all of the other recommended syntaxes, >>>>> replacing the declared class instead with an expression (similar to class >>>>> extension). >>>>> >>>>> Sent from my iPhone >>>>> >>>>> > On May 13, 2016, at 12:54 PM, /#!/JoePea <[email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: >>>>> > >>>>> > Perhaps a syntax based on modules: >>>>> > >>>>> > ```js >>>>> > try {} >>>>> > catch (TypeError as e) {} >>>>> > >>>>> > // ... >>>>> > >>>>> > try {} >>>>> > catch (MyError as err) {} >>>>> > ``` >>>>> > >>>>> >> On Fri, May 13, 2016 at 9:43 AM, Michał Wadas < >>>>> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> wrote: >>>>> >> I can't see why would your syntax be superior to SpiderMonkey >>>>> extension >>>>> >> except saving few characters. >>>>> >> >>>>> >> Can your syntax support code like this: >>>>> >> >>>>> >> async function foo() { >>>>> >> try { >>>>> >> throw new Error(); >>>>> >> } catch(e if isNativeException(e)) { >>>>> >> // special handler for DOM exceptions >>>>> >> } catch(e if e instanceof (await >>>>> >> fancyClassLoader.load('classes/SomeLibrary/UserDefinedError'))) { >>>>> >> // load class asynchronously if it wasn't loaded >>>>> >> } >>>>> >> } >>>>> >> >>>>> >> ? >>>>> >> >>>>> >> >>>>> >> On Fri, May 13, 2016 at 5:58 PM, Joseph Groseclose < >>>>> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> >>>>> >> wrote: >>>>> >>> >>>>> >>> I've updated the proposal. See: >>>>> >>> >>>>> https://github.com/benderTheCrime/error-type-specific-catch-proposal#about-spidermonkey-implementation >>>>> >>> >>>>> >>> On Fri, May 13, 2016 at 11:49 AM, Joseph Groseclose < >>>>> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> >>>>> >>> wrote: >>>>> >>>> >>>>> >>>> Nevertheless, perhaps the non-standard implementation could work >>>>> >>>> hand-in-hand with the proposal, where SpiderMonkey could support >>>>> both >>>>> >>>> solutions in parallel for backward compatibility. I think that >>>>> the proposed >>>>> >>>> solution is more expressive. >>>>> >>>> >>>>> >>>> On Fri, May 13, 2016 at 11:26 AM, Claude Pache < >>>>> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> >>>>> >>>> wrote: >>>>> >>>>> >>>>> >>>>> Note that SpiderMonkey has already nonstandard conditional catch >>>>> >>>>> clauses: >>>>> >>>>> >>>>> >>>>> ```js >>>>> >>>>> try { >>>>> >>>>> // ... >>>>> >>>>> } >>>>> >>>>> catch (e if e instanceof TypeError) { >>>>> >>>>> // .... >>>>> >>>>> } >>>>> >>>>> ``` >>>>> >>>>> >>>>> >>>>> —Claude >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> Le 13 mai 2016 à 17:06, Joseph Groseclose <[email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');>> a écrit >>>>> >>>>> : >>>>> >>>>> >>>>> >>>>> I sent this proposal via >>>>> >>>>> >>>>> http://www.ecma-international.org/memento/contribute_TC39_Royalty_Free_Task_Group.php# >>>>> >>>>> yesterday evening. Sharing it here now: >>>>> >>>>> >>>>> https://github.com/benderTheCrime/error-type-specific-catch-proposal >>>>> >>>>> >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> >>>>> es-discuss mailing list >>>>> >>>>> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');> >>>>> >>>>> https://mail.mozilla.org/listinfo/es-discuss >>>>> >>> >>>>> >>> >>>>> >>> _______________________________________________ >>>>> >>> es-discuss mailing list >>>>> >>> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');> >>>>> >>> https://mail.mozilla.org/listinfo/es-discuss >>>>> >> >>>>> >> >>>>> >> _______________________________________________ >>>>> >> es-discuss mailing list >>>>> >> [email protected] >>>>> <javascript:_e(%7B%7D,'cvml','[email protected]');> >>>>> >> https://mail.mozilla.org/listinfo/es-discuss >>>>> >> >>>>> >>>> >>>> >>> >>> _______________________________________________ >>> es-discuss mailing list >>> [email protected] >>> <javascript:_e(%7B%7D,'cvml','[email protected]');> >>> https://mail.mozilla.org/listinfo/es-discuss >>> >>> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> <javascript:_e(%7B%7D,'cvml','[email protected]');> >> https://mail.mozilla.org/listinfo/es-discuss >> >
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