This header-only library makes it easy to add command evaluation to a C++ program.
#include "command_interface.hpp"
class Arithmetic : public CommandInterface {
static int add(int x, int y) {
return x + y;
}
int inc(int x) {
return x + 1;
}
void register_commands() override {
register_command(add, "add", "Add two numbers");
register_command(&Arithmetic::inc, "inc", "Increment a number");
}
};A command is simply a function. Just register any function with a helper string; type safety occurs automatically.
We can create a simple REPL with the above interface.
#include <iostream>
int main() {
Arithmetic arithmetic;
std::string text;
std::cout << ">>> ";
while (std::getline(std::cin, text)) {
std::cout << arithmetic.eval(text) << std::endl << std::endl;
std::cout << ">>> ";
}
return 0;
}And then we have a command-line interface.
>>> help
add Add two numbers
inc Increment a number
help Show this help
>>> add 3 4
7
>>> inc 21
22
>>> add 3 4 5
Error: expected 2 arguments; got 3
>>> add 3 four
Error: invalid argument type at position 1; expected type i
Command Interface was created for adding a way to query state in microservices, like getting the list of outstanding orders in a trading system.
This library requires Boost's lexical cast and preprocessor macros.