On 7/11/2013 4:37 PM, Andrea Giammarchi wrote:
my problems is that generators were not needed there ... values() as
array of values, keys() as array of keys and items() as array of
key/value pairs.
This is even **easier**
Generators because you wrote them in PHP ... this, is non sense to me
(I am zend certified engineer if you are wondering)
Anyway, problem solved: harmony pages and examples in them are outdated.
Well to be more exact, the harmony page showed an example implementation
that used a generator, but that was never required. It was always called
for keys/values/entries to return an _iterator_, not a generator.
Generator functions are a convenient way to create iterators (becase
generators *are* iterators).
As an example, the following two implementations can be treated the same
for the purposes of iteration:
// ES6
function* entries(obj){
for (let key in obj) {
yield [key, obj[key]];
}
}
// ES3-5 version
function entries(obj){
var keys = [];
var index = 0;
for (keys[index++] in obj);
var total = index;
index = 0;
return {
next: function(){
if (index < total) {
var key = keys[index++];
return { done: false, value: [key, obj[key]] }
}
return { done: true };
}
};
}
In the same way, you can more succinctly demonstrate how Map/Set
iterators work using generators, but still could be implemented in ES3.
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