How do I return a variant type in D1?
After assessing that a variadic argument is an array, how do I check its
depth?
How do I set the variable given to me through the _arguments array?
thanks :)

Saaa wrote:
> How do I return a variant type in D1?
> After assessing that a variadic argument is an array, how do I check its depth?
> How do I set the variable given to me through the _arguments array?
> thanks :) 

Variant func()
{
	return variant(5);
}

If you want to return something given from a runtime variadic argument list, neither Tango's Variant nor Phobos's Variant will work. Tango's Variant will get this capability soon, I hear.

There is also reflect.variant:
svn co http://felt-project.org/reflect

reflect.variant allows you to create a Variant from a void* and a TypeInfo, like you get with varargs.

"Christopher Wright" <dhasenan@gmail.com> wrote in message news:gu8v1b$1uth$1@digitalmars.com...
> Saaa wrote:
>> How do I return a variant type in D1?
>> After assessing that a variadic argument is an array, how do I check its
>> depth?
>> How do I set the variable given to me through the _arguments array?
>> thanks :)
>
> Variant func()
> {
> return variant(5);
> }
I can't seem to find Variant in D1

>
> If you want to return something given from a runtime variadic argument list, neither Tango's Variant nor Phobos's Variant will work. Tango's
:(
> Variant will get this capability soon, I hear.

>
> There is also reflect.variant:
> svn co http://felt-project.org/reflect
>
> reflect.variant allows you to create a Variant from a void* and a TypeInfo, like you get with varargs.

Shouldn't it be possible to set an variadic argument?

void func( ... )
{
//something like this
cast(int) _argptr = 10;
}

Saaa wrote:
> "Christopher Wright" <dhasenan@gmail.com> wrote in message news:gu8v1b$1uth$1@digitalmars.com...
>> Saaa wrote:
>>> How do I return a variant type in D1?
>>> After assessing that a variadic argument is an array, how do I check its depth?
>>> How do I set the variable given to me through the _arguments array?
>>> thanks :)
>> Variant func()
>> {
>> return variant(5);
>> }
> I can't seem to find Variant in D1

In D1/Phobos, you can use std.boxer.Box, which can work with variadic arguments.

> In D1/Phobos, you can use std.boxer.Box, which can work with variadic arguments.
Ah, I see. boxer saves the typeinfo along the data.

Sorry to ask, but do you have an answer to my other question as well? Passing variadic arguments as ref I think is what I am asking for :)

Saaa wrote:
> ...
> Passing variadic arguments as ref I think is what I am asking for :)

You can't.  You have to explicitly take the address of the arguments.

  -- Daniel

> Saaa wrote:
>> ...
>> Passing variadic arguments as ref I think is what I am asking for :)
>
> You can't.  You have to explicitly take the address of the arguments.
>
>  -- Daniel

Like this ?
*_argptr = 10;
:D

I don't know how to tell the compiler I want to write data there.

Saaa wrote:
>> Saaa wrote:
>>> ...
>>> Passing variadic arguments as ref I think is what I am asking for :)
>> You can't.  You have to explicitly take the address of the arguments.
>>
>>  -- Daniel
> 
> Like this ?
> *_argptr = 10;
> :D
> 
> I don't know how to tell the compiler I want to write data there.

import std.stdarg;

assert( _arguments[0] is typeid(int*) );
auto arg = va_arg!(int*)(_argptr);
*arg = 10;

Probably.

  -- Daniel

I just noticed D1 does have std.stdarg.
I shouldn't just search on the website :(
(where it is missing on the phobos page)

> import std.stdarg;
>
> assert( _arguments[0] is typeid(int*) );
> auto arg = va_arg!(int*)(_argptr);
> *arg = 10;
>
> Probably.
:D
>
>  -- Daniel

So, you make arg point to the same as va_arg.
Why is this extra step necessary and why won't simple casting not work?

Saaa wrote:
> I just noticed D1 does have std.stdarg.
> I shouldn't just search on the website :(
> (where it is missing on the phobos page)
> 
>> import std.stdarg;
>>
>> assert( _arguments[0] is typeid(int*) );
>> auto arg = va_arg!(int*)(_argptr);
>> *arg = 10;
>>
>> Probably.
> :D
>>  -- Daniel
> 
> So, you make arg point to the same as va_arg.

No, va_arg is a function.

> Why is this extra step necessary and why won't simple casting not work?

You should never directly work with _argptr.  It's not guaranteed to be a simple pointer.  For example, I believe that GCC will sometimes use registers (God only knows WHY).

var_arg!(T) will convert _argptr into the type you specify and it will also advance _argptr to the next argument.

  -- Daniel