Variable Arguments using std.stdarg (and std.stdio)

Part of StandardLibraryCategory

Description

This demo shows typesafe variadic functions using std.stdarg and std.stdio.

VariadicFunctionsExample shows using printf.

VariableArgumentsExample shows a similar method of variable arguments using the std.c.stdarg module (which is now obsolete).

Example

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

import std.stdarg; 
import std.stdio;

class FOO{}

void foo(...)
{
    writefln("%s arguments\n", _arguments.length);
    for (int i = 0; i < _arguments.length; i++)
    {
        writef("%s", _arguments[i].toString);

        if (_arguments[i] == typeid(int))
        {
            int j = va_arg!(int)(_argptr);
            writefln("\t%s", j);
        }
        else if (_arguments[i] == typeid(long))
        {
            long j = va_arg!(long)(_argptr);
            writefln("\t%s", j);
        }
        else if (_arguments[i] == typeid(float))
        {
            float f = va_arg!(float)(_argptr);
            writefln("\t%s", f);
        }
        else if (_arguments[i] == typeid(double))
        {
            double d = va_arg!(double)(_argptr);
            writefln("\t%s", d);
        }
        else if (_arguments[i] == typeid(FOO))
        {
            FOO f = va_arg!(FOO)(_argptr);
            writefln("\t%s", f);
        }
        else if (_arguments[i] == typeid(char[]))
        {
            char[] c = va_arg!(char[])(_argptr);
            writefln("\t%s", c);
        }
        else
            assert(0);
    }
}



void main()
{
    FOO f = new FOO();
    foo(1, 2, 3L, 4.5, f, 7F, "my str");
}

Output

7 arguments

int     1
int     2
long    3
double  4.5
FOO     FOO
float   7
char[]  my str

Source

Link	http://www.dsource.org/tutorials/index.php?show_example=148
Posted by	jcc7