Null-aware function call? [duplicate]

Question

Dart has some null-aware operators, i.e. it is possible to do

var obj;
obj?.foo(); // foo is only called if obj != null.

Is this also possible for functions that are stored or passed to variables? The usual pattern is

typedef void SomeFunc();

void foo(SomeFunc f) {
  if (f != null) f();
}

It would be nice to have some null-aware calling here, like f?(). Is there anything we can use to not litter the code with null checks for those callbacks?

Hills

Answer 1

Form the docs:

Dart is a true object-oriented language, so even functions are objects and have a type, Function.

Apply the null aware ?. operator to the call method of function objects:

typedef void SomeFunc();

SomeFunc f = null;

f?.call();

Radiomicrometer

Thank you, this indeed works. From the docs alone, this wasn't clear to me (the "call()" is mentioned only for callable classes. But put together, it makes sense. – Hills

You can also use apply for this for more control : See https://mcmap.net/q/175648/-null-aware-function-invocation-operator – Traumatism