import std.conv : text;

import std.format : format;

​

// some function taking in just a string, defined somewhere in some library

void storeLogInDB(string severity, string logLine)

{

    // dummy implementation, we would actually want to call some DB API here

    import std.stdio;

    writefln(`call to storeLogInDB("%s", "%s")`, severity, logLine);

}

​

// our convenience functions we will be heavily using:

void logInfo(Args...)(Args args) { storeLogInDB("INFO", text(args)); }

​

// runtime format string

void logInfof(Args...)(string fmt, Args args) { storeLogInDB("INFO", format(fmt, args)); }

// compile-time format string (checked & optimized)

void logInfof(string fmt, Args...)(Args args) { storeLogInDB("INFO", format!fmt(args)); }

​

void main()

{

    logInfo("Logging important things: ", 1234);

​

    string failedLogin = "walter";

    int failedNum = 2;

    logInfof!"User %s failed login attempt %d"(failedLogin, failedNum);

}