Dart Object Pattern

TypeName(propertyName: subpattern, propertyName: subpattern)

// Explicitly binding the 'title' getter to a new variable 'docTitle'
final Document(title: docTitle, pageCount: count) = myDocument;

// Equivalent to Document(title: title, pageCount: pageCount)
final Document(:title, :pageCount) = myDocument;

// Matches a User whose 'address' property is an Address object 
// where the 'city' property matches the string 'Seattle'.
if (user case User(address: Address(city: 'Seattle'))) {
  // ...
}

// Extracts the length of the string returned by the 'name' getter
final User(name: String(:length)) = user;

// Matches if the Shape is a Circle and its radius getter returns a value >= 10
if (shape case Circle(radius: >= 10)) {
  // ...
}