losing argument ... as if assignment within condition has been a real problem except for JSLint ... uhm, I don't think so but I am off this conversation. Already said my point, feel free to (as usual) disagree ^_^
On Tue, Aug 27, 2013 at 9:48 AM, Brendan Eich <[email protected]> wrote: > On Aug 27, 2013, at 9:42 AM, Andrea Giammarchi < > [email protected]> wrote: > > sure you know everything as soon as you read `of` ... right ? > > > Wrong. The nested assignment is idiomatic in C but not good for everyone > (see gcc's warning when not parenthesized in such contexts) due to == and = > being so close as to make typo and n00b hazards. > > Furthermore, the exogenous binding / hoisting problem is objectively > greater cognitive load and bug habitat. > > > How objectives are your points ? If you know JS that while looks very > simple, IMO > > > Please learn when to fold a losing argument :-|. > > /be > > > > 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 >> >> >> >
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