I don't think it's pedantic to point out that you're misstating my argument. I didn't say "easy", I said "ergonomic", after all.
I've used bluebird quite a lot, and I've also used native promises and other promise libraries without filtered catch. At first, I missed this feature from bluebird, but I no longer do. Personally, I prefer the ergonomics of helper functions like I demonstrated to an overloaded `catch` method, especially one which does different things depending on the types of the arguments that are passed (one behavior for the instanceof check, another for a function predicate and another for an object predicate). Using an separate function gives the user a chance to specify exactly the behavior they want, no more and no less, and gives the user a chance to name the filter. Regards, Chris On Wed, Oct 11, 2017 at 5:28 AM, Michał Wadas <[email protected]> wrote: > I don't get why argument "it's easy to implement in user land" is raised. > > All Array methods are easy to implement in user land. Including recent > additions like .includes and ES2015 methods. > > Promises are easy to implement in user land. Smallest implementation is less > than 1kB AFAIR. > > Maps, Sets, WeakSets are trivial to implement in user land if WeakMap is > present. Probably less than 50 lines of code. > > Object.values, Object.entries, Object.assign, > Object.getOwnPropertyDescriptors, Object.is, Array.from, Array.of. These > methods were added recently but they can be implemented in user land. > > On 11 Oct 2017 2:28 am, "Christopher Thorn" <[email protected]> wrote: >> >> I agree that catch guards are useful, but they can be implemented in >> userland fairly ergonomically: >> >> ``` >> function guard(predicate, callback) { >> return function guarded(reason) { >> if (!predicate(reason)) { >> throw reason; >> } >> return callback(reason); >> }; >> } >> >> function instanceOf(constructor, callback) { >> return guard(reason => reason instanceof constructor, callback); >> } >> >> Promise.resolve('invalid') >> .then(JSON.parse) >> .catch(instanceOf(SyntaxError, reason => { >> // do something to handle the syntax error, or perhaps just silence it >> })); >> ``` >> >> Regards, Chris >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
