On 4/21/15 11:25 AM, "Marc =?UTF-8?B?U2Now7x0eiI=?= <[email protected]>"
wrote:
On Tuesday, 21 April 2015 at 14:25:29 UTC, Steven Schveighoffer wrote:
On 4/21/15 10:07 AM, Chris wrote:
Here's bearophile's version of sorting an AA by value [1]
void main() {
import std.stdio: writeln;
import std.algorithm.sorting: multiSort;
import std.array: array;
const size_t[string] wCount = [
"hamster": 5,
"zorro": 80,
"troll": 90,
"algorithm": 80,
"beer": 80
];
auto pairs = wCount.byKeyValue.array;
assert(wCount.length == pairs.length);
pairs.multiSort!(q{a.value > b.value}, q{a.key < b.key});
assert(pairs[2].key == "beer");
foreach (const ref it; pairs)
writeln(it.key, ": ", it.value);
}
Should we add it to the documentation of
1. http://dlang.org/phobos/std_algorithm_sorting.html#.multiSort
2. http://dlang.org/hash-map.html
We should not be promoting string-based lambdas:
pairs.multiSort!((a, b) => a.value > b.value, (a, b) => a.key < b.key);
I find the strings to be more readable, simply because they are shorter.
I would probably even prefer normal "" quotes.
quoted lambdas are indeed shorter, but the issue with them is that "a<b"
instantiates a different template than "a < b", whereas the lambda does not.
In fact, that is why we added shorthand lambdas to the language. Note
that in this case, it's just wasted code space and not a real issue. but
for example, RedBlackTree!(int, "a < b") is not compatible with
RedBlackTree!(int, "a<b"), even though they are identical.
I'm not saying we shouldn't allow string lambdas, just that we shouldn't
encourage them as "proper" D code.
I think this would be a perfect addition for the disqus forum of that
function (once ddox gets to be the default). I don't want to get into
adding sample usages for every use case on every function to the
documentation.
Not for every possible use case, but I'd prefer examples demonstrating
an actual, practical application to ones that were just made up for the
sake of documentation.
This use case seems niche to me. I haven't ever had the need to "sort"
an AA, and if I did, I would use a RedBlackTree.
Not discounting it, or saying it's not valid or useful, just that it's
not such a perfect example that it needs to unseat the current example
(sorting points by x and y).
It definitely does not belong in the AA documentation.
-Steve
