// tag
#format
2 posts tagged #format.
C++26 rewrote std::print's internals and backported the fix
std::print's per-call atomicity extends to your own types via std::formatter. How it stays both safe and efficient is a C++26 story: P3107 adds locking-aware entry points and a formatter opt-in to avoid deadlock, and ships as a backport into C++23. Episode 5 of the concurrent I/O series.
Why you can't std::format a smart pointer (and how to anyway)
A recent r/cpp question: std::cout << a unique_ptr works, but std::println("{}", that_unique_ptr) is ill-formed. There is no std::formatter for smart pointers. Is that an oversight? No -- it is a deliberate, sustained decision. Here is the why, and three ways to format a smart pointer today, all verified on Compiler Explorer.