How can I check if argument is null, and if not use it in a function?-CodePudding

Is there a shorter, more elegant way to do that?

var? x = null == y ? null : foo(y!);

Something like this, maybe?

int? y = null;
double? x = y?.toDouble() ?? null;

(it should be null safe as well)

CodePudding user response：

No.

There is currently no operation in Dart which takes a value, checks if it is non-null, and if so, does something to it other than calling a method on the object.

What you can do, if you want to, is to introduce an extension like

extension CallWith<T> on T {
   R pipeTo<R>(R Function(T) f) => f(this);
}

Then you can write:

  y?.pipeTo(foo);

CodePudding user response：

there is the null aware operator ??

String? nullableString;
String notnullableString = nullableString ?? "this returns when nullableString is null";

Null Aware Operators in Dart