Change range adaptor examples to print with formatting ranges #5908

brevzin · 2022-10-19T00:11:16Z

Currently, every range adaptor starts with a very short example that prints the contents of an adapted range. For instance, transform has:

vector<int> is{ 0, 1, 2, 3, 4 };
auto squares = views::transform(is, [](int i) { return i * i; });
for (int i : squares)
  cout << i << ' '; // prints 0 1 4 9 16

adjacent has:

vector v = {1, 2, 3, 4};

for (auto i : v | views::adjacent<2>) {
  cout << "(" << std::get<0>(i) << ", " << std::get<1>(i) << ") ";  // prints (1, 2) (2, 3) (3, 4)
}

chunk has:

vector v = {1, 2, 3, 4, 5};

for (auto r : v | views::chunk(2)) {
  cout << '[';
  auto sep = "";
  for (auto i : r) {
    cout << sep << i;
    sep = ", ";
  }
  cout << "] ";
}
// The above prints [1, 2] [3, 4] [5]

We can now change all of these loops (some of which are nested) to just a call to print, which will make the examples smaller and also provide more information. For instance, the adjacent example doesn't actually make clear that it gives you a 2-tuple back. The above can be turned into:

vector<int> is{ 0, 1, 2, 3, 4 };
auto squares = views::transform(is, [](int i) { return i * i; });
print("{}", squares); // prints [0, 1, 4, 9, 16]

and

vector v = {1, 2, 3, 4};
print("{}", v | views::adjacent<2>); // prints [(1, 2), (2, 3), (3, 4)]

and

vector v = {1, 2, 3, 4, 5};
print("{}", v | views::chunk(2)); // prints [[1, 2], [3, 4], [5]]

Is there any reason to not do this?

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jwakely · 2022-10-19T00:45:00Z

I think there is some value in the adjacent example which shows that the range elements are tuple-like. It doesn't tell you it's not a tuple with more than 2 elements, but it does show it's something tuple-like. And the chunk example shows you get a range of ranges, not e.g. a range of pairs (I know pairs would be printed differently, but if you don't know that, the suggested replacement "hides" that info).

But I think I still prefer your suggested replacements anyway. They're less cluttered, even if that clutter in the originals has some info about the ranges.

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Change range adaptor examples to print with formatting ranges #5908

Change range adaptor examples to print with formatting ranges #5908

brevzin commented Oct 19, 2022

jwakely commented Oct 19, 2022

Change range adaptor examples to print with formatting ranges #5908

Change range adaptor examples to print with formatting ranges #5908

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brevzin commented Oct 19, 2022

jwakely commented Oct 19, 2022