dart optional parameters
// Dart Optional Positional Parameters
void myFunction(String name1, String name2, [String name3]) {
// ...name3 is optional, and after required parameters
}
// Dart Optional Named Parameters
void myFunction(int x, {int y = 2}) {
// ...y is optional, default is 2
}
myFunction(2, y: 4); // sequence does not matter
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Curly brackets {} are used to specify optional, named parameters in Dart.
readFile(String name, {String mode, String charset = 'utf-8'}) {
// empty
}
Named parameters are referenced by name,
which means that they can be used during the function
invocation in an order different from the function declaration.
readFile('hello.dart');
readFile('hello.dart', mode: 'w+');
readFile('hello.dart', charset: 'iso8859-1');
readFile('hello.dart', charset: 'iso8859-1', mode: 'w+');
readFile('hello.dart', mode: 'w+', charset: 'iso8859-1');
Thank you!
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