CODEWITHSUNDEEP
argumentsdartoptional-parameters
Letsgo
Letsgo

Reputation: 711

How to access or iterate parameters in Dart

In a function with optional parameters, I want to print all the parameters passed in, not just value but also identifier of each parameter. For example, below is a function with optional named parameters. I print out both arg name and its value using a map instance, that's what I need.

Map temp = new Map();

argumentTest({String a, String b, String c: "DDD"}){
  if (a != null) {
    temp.addAll({"a":a});
  }

  if (b != null) {
    temp.addAll({"b":b});
  }

  if (c != null) {
    temp.addAll({"c":c});
  }
}

void main() {
  argumentTest(a:"AAA");
  print('$temp'); //{a: AAA, c: DDD}

}

Though ugly, it works. But, is there anything which looks like;

Map temp = new Map();

argumentTest({String a, String b, String c: "DDD"}){
  arguments.forEach((arg) => temp.addAll({"arg": arg}));
}

void main() {
  argumentTest(a:"AAA");
  print('$temp'); //of course, not working.
}

Thank you all and always.

Upvotes: 2

Views: 1226

Answers (3)

Günter Zöchbauer
Günter Zöchbauer

Reputation: 657416

You could simplify your workaround

Map temp = new Map();

argumentTest({String a, String b, String c: "DDD"}) {
  ({'a': a, 'b': b, 'c': c}).forEach((k, v) {
    if(v != null) temp[k] = v;
  });
}

to support default values different from null you need to extend a little - for example like

argumentTest({String a, String b, String c: "DDD"}) {
  ({
      'a': [a, null], 'b': [b, null], 'c': [c, "DDD"]
  }).forEach((k, v) {
    if(v[0] != v[1]) temp[k] = v[0];
  });
}

Upvotes: 4

luizmineo
luizmineo

Reputation: 966

There is no such thing in Dart. However, if you want to build mock objects for automated tests, you can take a look at this article, which shows how to use the mock package

Upvotes: 2

Danny Tuppeny
Danny Tuppeny

Reputation: 42343

I don't believe this is possible (even using mirrors). The names of your variables will be changed during minification. The "messy" coder you have is really the only way of preserving them in a way you can access like this.

Upvotes: 1

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