Le 27 août 2013 à 18:48, Andrea Giammarchi <[email protected]> a
écrit :
> let me rephrase ... I've no idea what this code does if not a syntax error
> (and for different reasons)
>
> `for (let m of re.execAll(str) {`
>
> what is `of` ... will `let` mark that variable as local ? what is returned
> and what will be `m` ?
>
> I need to know these things ... this has nothing to do with "Don’t be clever,
> don’t make me think." a point which also I don't understand (I have to think
> about such statement ... I don't demand Ocaml language to be C like 'cause I
> don't get it)
Trying to reexplain: `for (let m of re.execAll(str))` is a direct, one-to-one
translation of the meaning of the programmer into (the expected) EcmaScript 6.
But with `while (m = re.exec(str))`, you exploit some secondary fact about the
value of `re.exec(str)` (falsy iff when over) which is unrelated to the object
of the code. (And yes, you have to learn the complete syntax of `for/of` in
order to understand the code, but it is unrelated to the point.)
—Claude
>
> Anyway, I've already commented my point of view.
>
> Regards
>
>
> On Tue, Aug 27, 2013 at 9:42 AM, Andrea Giammarchi
> <[email protected]> wrote:
>> sure you know everything as soon as you read `of` ... right ? How objectives
>> are your points ? If you know JS that while looks very simple, IMO
>>
>>
>> On Tue, Aug 27, 2013 at 5:24 AM, Claude Pache <[email protected]> wrote:
>>>
>>> Le 27 août 2013 à 01:23, Brendan Eich <[email protected]> a écrit :
>>>
>>> > Andrea Giammarchi wrote:
>>> >> Is it very useful because you wrote for instead of while ?
>>> >>
>>> >> ```javascript
>>> >> while (m = re.exec(str))
>>> >> console.log(m[0])
>>> >> ;
>>> >> ```
>>> >
>>> > It is, for two reasons:
>>> >
>>> > 1. in JS only for can have a let or var binding in the head.
>>> >
>>> > 2. the utility extends to all for-of variations: array comprehensions,
>>> > generator expresisons.
>>> >
>>> > /be
>>>
>>> There is a third reason. The syntax:
>>>
>>> ```javascript
>>> for (let m of re.execAll(str) {
>>> // ...
>>> }
>>> ```
>>>
>>> has the clear advantage to express the intention of the programmer, and
>>> *nothing more*. It does not require good knowledge of the details of the
>>> language to understand what happens.
>>>
>>> Indeed, when I read `while(m = re.exec(str))`, I really have to analyse the
>>> following *additional* points:
>>> * `=` is not a typo for `==` (here, some annotation would be useful);
>>> * `RegExp#exec` returns a falsy value if *and only if* there is no more
>>> match;
>>> * `re` has its global flag set, and its `.lastIndex` property has not been
>>> disturbed.
>>>
>>> All these tricks are unrelated to the intention of the programmer, and are
>>> just distracting points, especially for any reader that use only
>>> occasionally `RegExp#exec` with the global flag set.
>>>
>>> In summary, citing [1]: "Don’t be clever, don’t make me think."
>>>
>>> —Claude
>>>
>>> [1] http://www.2ality.com/2013/07/meta-style-guide.html
>
_______________________________________________
es-discuss mailing list
[email protected]
https://mail.mozilla.org/listinfo/es-discuss
