Guided Refactoring Test

Refactoring demo

How to write expressive C++ for the following problem?

is any of the numbers positive?

Step 1: Initial state

Legacy for-loop (range based)

Step 2: Use standard algorithms

Replace loop with any_of

Step 3: Use ranges

Cleanup iterator verbosity using ranges library

Step 4: Use named predicate

Cleanup lambda syntax

Step 5: Use type alias

Cleanup namespacing from statement

Step 1

bool is_any_positive = false;
for(int value : numbers) {
  if (value > 0) {
      is_any_positive = true;
      break;
  }
}

Step 2

bool is_any_positive = false;
for(int value : numbers) {
  if (value > 0) {
      is_any_positive = true;
      break;
  }
}
bool is_any_positive = std::any_of(
       numbers.cbegin(),
       numbers.cend(),
       [](const int value) { return value > 0; });
}

Step 3

bool found = std::any_of(
       numbers.cbegin(),
       numbers.cend(),
       [](const int value) { return value > 0; });
}
bool is_any_positive = std::ranges::any_of(numbers,
       [](const int value) { return value > 0; });

Step 4

bool is_any_positive = std::ranges::any_of(numbers,
       [](const int value) { return value > 0; });

const auto is_positive = [](const int value) { return value > 0; };
bool is_any_positive = std::ranges::any_of(numbers, is_positive);

Step 5

using std::ranges::any_of;
const auto is_positive = [](const int value) { return value > 0; };

bool is_any_positive = std::ranges::any_of(numbers, is_positive);
bool is_any_positive = any_of(numbers, is_positive);

See also

• Use Named Predicates to improve readability when using algorithms