tree 7bbcba89d90f72be457a32bba25926a202dad348
parent 6b0190f746976a2e3b26ed529a9d487ae2587868
author msta <msta@google.com> 1786335234 +1000
committer gn-scoped@luci-project-accounts.iam.gserviceaccount.com <gn-scoped@luci-project-accounts.iam.gserviceaccount.com> 1786501207 -0700

Implement a Result<T> type.

Output parameters are an antipattern that should be avoided in C++.

They have a minor performance overhead from the inability to use RVO,
but more importantly, they're extremely unergonomic to use. Unless
you're specifically passing a potentially non-empty object by reference,
you should generally avoid using them.

https://www.dominikgrabiec.com/posts/2022/02/20/cpp_antipattern_passing_result_array_in.html

Google3 has had absl::StatusOr and RETURN_IF_ERROR / ASSIGN_OR_RETURN
since I first started in 2018. With the advent of C++23, we now have
std::expected.

These are equivalent to rust's "?" operator. They significantly improve
readability and make it much harder to write incorrect code (eg.
ignoring the error value).

See go/totw/121 if you're a googler for more details

Change-Id: If32e4c953f9cdfe4c3764eb01970d2596a6a6964
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/25140
Commit-Queue: Matt Stark <msta@google.com>
Reviewed-by: Takuto Ikuta <tikuta@google.com>