On Saturday, 9 March 2013 at 09:32:43 UTC, Andrea Fontana wrote:
On Saturday, 9 March 2013 at 09:13:26 UTC, Andrea Fontana wrote:
On Saturday, 9 March 2013 at 01:36:53 UTC, bearophile wrote:
Is it a good idea to replace std.algorithm.filter with
something like that filter2 (plus some missing methods)?
Bye,
bearophile
Maybe two versions (filter and cachedFilter) or a bool
template param?
I was thinking about @pure front() too: but I think it's a
wrong assumption. The right assumption would be that front
should return the same value until popFront is called again.
It can read front value lazily from front() call. It can do a
lot of impure things (lol) but it shouldn't change front
"randomly" at each call.
I would improve distinct to support an alias pred = "a < b" to
build a bst instead of an AA.
Or just a field like distinct!"a.id" (that should work with aa
backend)
I almost got it:
auto distinct(alias fun = "a", Range)(Range r)
if (isInputRange!Range) {
alias unaryFun!fun _fun;
bool[ReturnType!_fun] mySet;
return r.filter2!((k) {
if (_fun(k) in mySet)
return false;
mySet[_fun(k)] = true;
return true;
});
}
ReturnType!_fun doesn't work, if i set to the right type,
function works as expected
auto distinct(alias fun = "a", Range)(Range r)
if (isInputRange!Range) {
alias unaryFun!fun _fun;
bool[typeof(_fun((ElementType!Range).init))] mySet;
return r.filter2!((k) {
if (_fun(k) in mySet)
return false;
mySet[_fun(k)] = true;
return true;
});
}
struct User
{
int id;
string name;
}
void main() {
User[] users = [ {1, "first"}, {2, "second"}, {3, "first"}];
users.distinct!("a.id")().writeln;
users.distinct!("a.name")().writeln;
}
this works. Is this:
bool[typeof(_fun((ElementType!Range).init))] mySet;
the right way?
