View source code
Display the source code in object.d from which this page was generated on github.
Report a bug
If you spot a problem with this page, click here to create a Bugzilla issue.
Improve this page
Quickly fork, edit online, and submit a pull request for this page. Requires a signed-in GitHub account. This works well for small changes. If you'd like to make larger changes you may want to consider using local clone.

Function object.update

Calls create if key doesn't exist in the associative array, otherwise calls update. create returns a corresponding value for key. update accepts a key parameter. If it returns a value, the value is set for key.

void update(K, V, C, U) (
  ref V[K] aa,
  K key,
  scope C create,
  scope U update
if (is(typeof(create()) : V) && (is(typeof(update(aa[K.init])) : V) || is(typeof(update(aa[K.init])) == void)));


aa The associative array.
key The key.
create The callable to create a value for key. Must return V.
update The callable to call if key exists. Takes a K argument, returns a V or void.


int[string] aa;

// create
    () => 1,
    (int) {} // not executed
writeln(aa["key"]); // 1

// update value by ref
    () => 0, // not executed
    (ref int v) {
        v += 1;
writeln(aa["key"]); // 2

// update from return value
    () => 0, // not executed
    (int v) => v * 2
writeln(aa["key"]); // 4

// 'update' without changing value
    () => 0, // not executed
    (int) {
        // do something else
writeln(aa["key"]); // 4


Walter Bright, Sean Kelly


Boost License 1.0.