Arrow function support in ES6.

[steverobb]

Support for ES6 arrow function in autoInject:

async.autoInject({
    task1: (cb)        => cb(null, 1),
    task2: (task3, cb) => cb(null, 2),
    task3: cb          => cb(null, 3)
}, (err, task3, task1) => {
    // use task1 and task3
});

[megawac]

don't use .trim() it doesn't have sufficient vendor support. Either import lodash/trim or use a different approach. Is it necessary?

[steverobb]

The trim is necessary because it doesn't support spaces around the function name parameters, e.g. function( x, y, z ), and then there was a space after the final parameter. This wasn't obvious until I added support for arrow functions like x => y. I tried inventing a regex which coped with both functions and arrows, but failed, and the trim seemed like an easy workaround.

Alternatively, it could import a dedicated library, e.g.: https://www.npmjs.com/package/get-parameter-names

[steverobb]

Its entire purpose is to 'auto-sniff' to aid readability, otherwise you'd just use auto. What is the objection here?

[steverobb]

It's not my library, so it's not my call, but these issues have already been considered:

#608 (comment)

[steverobb]

That's one opinion. But if you wish to see it removed, I think you should raise an issue ticket. This is not the correct forum.

[steverobb]

This is not about you or your reputation. You have a valid opinion and I encourage you to raise it for discussion. Just not in the patch comments of this tangentially-related PR.

[aearly]

Yeah, sniffing parameters is the whole point of autoInject. By using it, you accept all the caveats associated with that approach. If you don't want it, you can use auto (or the array-style form for tasks).

[aearly]

@jdalton any ideas on how to feature-detect native arrow-function support for testing?

[jdalton]

Don't forget about default params:

function a(b=1) {}
a+''
// => "function a(b=1) {}"

or comments in IE 11:

function a(/*b,c,*/d) {} 
a+'' 
// => "function a(/*b,c,*/d) {}" 

or bound functions:

function a(b,c) {}
var b = a.bind({})
b+''
// => "function () { [native code] }"

[aearly]

We'll just document that all of those don't work.

[aearly]

One idea I have to feature detect is to use eval for the whole test. If eval("()=>1") throws, we know arrow funcs aren't supported. Then we can do an eval on the rest of the test body to test the feature. Seems really clunky though.

[megawac]

Nope, it would syntax error when you load the file. Unless you want to eval
the entire test ^^

On Wed, May 4, 2016 at 11:52 PM, Alex Early [email protected]
wrote:

One idea I have to feature detect is to use eval for the whole test. If
eval("()=>1") throws, we know arrow funcs aren't supported. Then we can
do an eval on the rest of the test body to test the feature. Seems really
clunky though.

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#1125 (comment)

[aearly]

Yeah, we'd eval the whole test....

[steverobb]

By the way, though the check-in messages doesn't suggest it, these recent commits utilise eval to allow ES6-only tests.

[aearly]

Ah sorry, I didn't notice you had pushed those changes. It looks like there's now some conflicts -- can you resolve them?

[steverobb]

Done!