CODEWITHSUNDEEP
c++c++11lambda
djWann
djWann

Reputation: 2127

Lambda function returning auto like behaviour

I'm having problems trying to create the following lambda function:

const auto var x = [&y]() -> /*???*/ {
if (y == type1) {
  return some_type_1;
} else if (y == type2) {
  return some_type_2;
} else // ...

I know I cannot use auto as return type. But how can I do it in another way?

Thanks!

Upvotes: 1

Views: 106

Answers (1)

ecatmur
ecatmur

Reputation: 157414

If some_type_1 and some_type_2 have a common type, write:

const auto var x = [&y]() -> typename std::common_type<
  decltype(some_type_1),
  decltype(some_type_2)>::type {
if (y == type1) {
  return some_type_1;
} else if (y == type2) {
  return some_type_2;
} else // ...

Equivalently, you can use a ternary expression:

const auto var x = [&y]() {
  (y == type1) ? some_type_1 :
  (y == type2) ? some_type_2 :
  ...;
}

Upvotes: 2

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