Named Paramters

[Soni L.]

Could add f{} as sugar for f({}), and make engines optimize f{}? (no 
positional arguments though)

On 31/07/15 12:00 PM, Michał Wadas wrote:
> Proposal that do not conflict with minimifiers:
>
> - Functions have optional named parameters in any place of argument
> definition. Optionality is defined by presence of hash character at
> beginning of parameter name. Optional parameters CAN be placed after
> rest parameter. These parameters can be accessed by name or by
> position:
>
> ```
> function foo(bar, #qaz, boo) {
> return [bar, qaz, boo];
> }
> foo(1,2,3); // [1,2,3]
> foo(#qaz: 3, 4, 1); // [4,3,1] or [4,1,undefined] or throw?
>
> function faz(bar, ...baz, #qoo) {
> return [bar, ...baz, qoo];
> }
> faz(1,2,3,4,#qoo:5); // [1,2,3,4,5]
>
> function print(...toPrint, #delimiter=',', newLine='\n') {
> console.log(toPrint.join(delimiter)+newLine);
> }
> let delimiter = ':';
> print(1, 2, 3, 4, 5,#{delimiter}); // prints '1:2:3:4:5\n'
>
> ```
>
> Possible solutions for nonexistant optional argument (eg. foo(#nope:null) ):
> - throw (probably the worst solution )
> - define `arguments[Symbol.optionals]` object (great for passing
> optional arguments)
> - allow syntax for "rest optional parameters"
> - ignore
>
> Some problems:
> - probably this syntax can not be transpiled in general case
> - there is no intuitive behavior for ` print (1,2, #delimiter:' ',
> #{delimiter})`
> - how will `.apply` work? Third argument with optional arguments?
> `Symbol.optionals`  property on second argument (good for
> seaminglessly passing `arguments`, but it doesn't sound like good idea
> for arrays)?.
> -
>
> Any thoughts?
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