DP::DUMP

Introduction

A creation of the proposed debug tool from P2879R0: Proposal of std::dump - a tool to quickly dump a set of data. In summary,

dp::dump(a,b,c,d);

is equivalent to

std::print("{} {} {} {}", a, b, c, d);

including the necessary overloads for std::FILE* and std::ostream output, as well as dp::dumpln to insert a newline after the dump of variables.

This tool supports both C++20 and C++23 with no additional dependencies, as it is powered by std::print on implementations which have it and std::format otherwise. It is also possible to use this tool on C++14 and C++17, using the fmt library, and passing DP_DUMP_USE_FMTLIB as a preprocessor define. Taking this approach obviously requires fmt as a dependency.

Installation

This tool is a single header. Just download and #include it, and away you go.

Sample Code

For a main file

#include "dump.h"
#include <fstream>

int main(){
	std::ofstream os{"Some_output_file.txt"};
	dp::dumpln(os, 1, 2, 3);
};

When compiled to the C++23 standard, this will call std::println to place 1 2 3 into the output file specified. If compiled with -DDP_DUMP_USE_FMTLIB (or your platform's equivalent) and linked with fmtlib, you will get the same observible behaviour as if fmt::print(os, "{} {} {}", 1, 2, 3); had been called.

FAQ

• Can I use libfmt over the standard functions in C++20 and C++23? Yes, defining DP_DUMP_USE_FMTLIB will mean fmt is used regardless of your C++ version and what tools are supported.

• Does using std::format mean that this function allocates? Why not use a different approach? This was considered during development, but ultimately std::format was chosen. The reasons were simple - requiring an operator<< overload in implementations without std::print and a std::formatter specialisation in implementations with it adds a high degree of inconsistency which was deemed unacceptable. It is far preferable for the user to need only define a formatter for their desired type and call it a day. If this still leaves a bad taste in your mouth, you can use the fmtlib version of this library.