See https://github.com/zkat/proposal-as-patterns
On Wed, Jan 16, 2019 at 12:24 AM Sultan <[email protected]> wrote: > The ability to both name and de-structure an argument. > > Relying on the spread operator does not archive the same effect > considering that the spread operator "by design" has some short-comings > related to exotic objects when the objects in question have a rich > prototype you want to preserve. > > Consider the following proposal: > > function fn (arg pick {a, b = arg.b = 'value'}) {} > > This would allow four fundamental things of note missing from current > de-structuring status-quo: > > 1. The ability to have both named arguments and de-structuring. > > 2. The ability to reference the named argument within the de-structure. > This allows the above pattern of setting a default value on the passed > argument when it doesn't exist. > > 3. This in turn also affords you the ability to de-structure while also > preserving the exotic nature of an object when it is not a POJO object. > > That is when "arg" is an exotic use-defined object using the spread > operator "{...arg}" will discard its prototype. > > For example: > > function a ({a, ...b}) { return b } > > a([1, 2]) > > Returns a object with index-able keys instead of the array. > > 4. Consequently this addition would also afford the avoidance of any > overhead that one might want to avoid with the rest spread operation: {a, > b, ...arg} in hot paths. > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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