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Function object.byKey

Returns a forward range which will iterate over the keys of the associative array. The keys are returned by reference.

auto byKey(T, K, V) (
  T aa
) pure nothrow @nogc @safe;

auto byKey(T, K, V) (
  T* aa
) pure nothrow @nogc;

If structural changes are made to the array (removing or adding keys), all ranges previously obtained through this function are invalidated. The following example program will dereference a null pointer:

import std.stdio : writeln;

auto dict = ["k1": 1, "k2": 2];
auto keyRange = dict.byKey;
writeln(keyRange.front);    // Segmentation fault


aa The associative array.


A forward range referencing the keys of the associative array.


auto dict = [1: "v1", 2: "v2"];
int sum;
foreach (v; dict.byKey)
    sum += v;

writeln(sum); // 3


Walter Bright, Sean Kelly


Boost License 1.0.