Variadic Functions

Part of StandardLibraryCategory

Description

This demo shows typesafe variadic functions (requires DMD 0.93+). It uses std.stdarg and printf.

VariableArgumentsUsingStdStdargExample shows using writef instead of printf.

Example

/* To protect against the vagaries of stack layouts on different CPU architectures, 
use std.stdarg to access the variadic arguments: */

import std.stdarg; 

class FOO{}

void foo(...)
{
    printf("%d arguments\n", _arguments.length);
    for (int i = 0; i < _arguments.length; i++)
    {   _arguments[i].print();

        if (_arguments[i] == typeid(int))
        {
            int j = va_arg!(int)(_argptr);
            printf("\t%d\n", j);
        }
        else if (_arguments[i] == typeid(long))
        {
            long j = va_arg!(long)(_argptr);
            printf("\t%lld\n", j);
        }
        else if (_arguments[i] == typeid(double))
        {
            double d = va_arg!(double)(_argptr);
            printf("\t%g\n", d);
        }
        else if (_arguments[i] == typeid(FOO))
        {
            FOO f = va_arg!(FOO)(_argptr);
            printf("\t%p\n", f);
        }
        else if (_arguments[i] == typeid(char[]))
        {
            char[] c = va_arg!(char[])(_argptr);
            printf("\t%.*s\n", c);
        }
        else
            assert(0);
    }
}


void main()
{
    FOO f = new FOO();

    printf("%p\n", f);
    foo(1, 2, 3L, 4.5, f, "my str");
}

Output

    00870FD0
    5 arguments
    int
        1
    int
        2
    long
        3
    double
        4.5
    FOO
        00870FD0

Source

Pieced together from examples in the D Specification.

Link	http://www.dsource.org/tutorials/index.php?show_example=101
Posted by	jcc7