On Jul 30, 2010, at 2:47 PM, felix wrote: > On 7/30/10 14:37, Brendan Eich wrote: >> For Harmony, we do not propose to standardize |for each|. Instead, the >> iteration and array comprehensions proposals for Harmony (see the wiki) >> propose that programmers choose keys, values, items (properties), or other >> iteration protocols by saying what they mean more precisely on the >> right-hand side of 'in': >> >> for (k in keys(o)) ... >> for (v in values(o)) ... >> for ([k, v] in properties(o)) ... // Python's "items" >> >> This seems better in TC39 members' views than adding ambiguous 'each' as a >> contextual keyword. > > I'm wary of that because this looks to me confusing: > a = keys(o); > for (k in a) ...
The confusion here seems to be assuming that |a| is an Array instance. It's not. It is an iterator, so you'll get the keys (property names) found in o -- you won't get 0, 1, ... a.length-1. To avoid this confusion you can add new syntax (|for each| or whatever, doesn't matter). I've argued in recent posts that it is better from a global and long-term point of view to reform for-in after Python, than to condemn it and grow the language with new and generally more verbose, yet similar, syntax. > or is keys(o) special syntax that only works within a for() statement? No. /be _______________________________________________ es-discuss mailing list es-discuss@mozilla.org https://mail.mozilla.org/listinfo/es-discuss
