On 23 Apr 2025 01:27, Aaron Graham via Boost wrote:
I'd like to gauge the interest in adding the following library to boost: https://github.com/rokudev/rostd/blob/main/include/rostd/printx.hpp
It's a simple library that checks and rewrites the format string at compile time in order to fortify it for use with printf, leaving the object code with only a call to the underlying C-standard printf-family function.
It's a single header and requires C++20 or above (for cNTTP support). It contains these four functions: printf, sprintf, snprintf, fprintf
These functions are used like so:
printf<"Hello %s\n">("World!");
char buf[20]; sprintf<"Hello %s\n">(buf, "World!"); // yes, it's safe
char buf[20]; snprintf<"Hello %s\n">(buf, sizeof buf, "World!");
fprintf<"Hello %s\n">(file, "World!");
Features/rationale:
* It provides old-style printf (supports all standard printf specifiers). * Fully type-safe. No format string attacks. Issues are found at compile time. * Length modifiers are deduced; these format strings are portable. (No PRIu64 inttypes stuff needed anymore, just use %u) * Adds %? format specifier (print whatever type is there). * Compiles to std::printf (much smaller object code than std::format). * Provides a way for developers to easily adapt this printf formatting capability to their own functions (logging, etc.)
More detailed rationale is here: https://github.com/rokudev/rostd/blob/main/doc/printx.adoc
Seems like a neat lightweight alternative to std::format. Though the documentation could better cover the comparison against std::format, in particular wrt. compile times and binary sizes. I suspect, the question of "why not just std::format" will be one of the most often asked. Extensibility is also a point of interest. Lack of extensibility of std::printf is often #1 reason why other alternatives are used. It would be very much desirable if the proposed library tackled this limitation, at least to some extent.