assert(expression, error)

[Andrej Mitrovic]

Yeah, enforce is great. Here's one way I use it for external libraries
in one of my projects:

class sndfileException : Exception
{
    this(SNDFILE *sndfile)
    {
        super(to!string(sf_strerror(sndfile)));
    }
}

auto handle = sf_open(args);  // on failure returns null
enforce(handle !is null, new libsndException());

The sf_strerror function is from a library function that returns a C
string with the last error that occurred for a specific handle
(SNDFILE*). So I just made a simple exception wrapper for it in the
libsndException class.