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digitalmars.D.learn - variadic (typesafe) args in DLL

reply Bjoern <nanali nospam-wanadoo.fr> writes:
Hi,
I hope that I can write a small utility DLL which offers support for :

BinaryOrPlus(WS_TABSTOP, WS_CHILD, WS_CLIPSIBLINGS)

Why ? Because my 4GL has no binary OR operator (just a function) so this 
code fragment will not work :

x is unsigned int = WS_TABSTOP | WS_CHILD | WS_CLIPSIBLINGS    // etc.

Instead I have to use :
(BinaryOr(BinaryOr(WS_TABSTOP , WS_CHILD), WS_CLIPSIBLINGS)  // stinks !

I hope it is possible to create something similar to :

export extern (Windows) uint BinaryOrPlus(uint...)
{
   uint result = _arguments[0];
   for (int i = 1; i < _arguments.length; i++)
   {
      result |= _arguments[i];
   }
   return result;
}

Unfortunately Error msg is :

C:\dmd\projects\bsdutil>dmd -profile -odc:\dmd\projects\bsdutil\obj 
-ofBSDUTIL.D
LL bsdutil.d demangle.d bsdutil.def
bsdutil.d(110): Error: undefined identifier _arguments
bsdutil.d(110): Error: _arguments must be an array or pointer type, not int

etc. I use Tango.
??????
Bjoern
Feb 08 2008
parent reply "Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
"Bjoern" <nanali nospam-wanadoo.fr> wrote in message 
news:foi37b$19vv$1 digitalmars.com...


 export extern (Windows) uint BinaryOrPlus(uint...)
 {
   uint result = _arguments[0];
   for (int i = 1; i < _arguments.length; i++)
   {
      result |= _arguments[i];
   }
   return result;
 }

 Unfortunately Error msg is :

 C:\dmd\projects\bsdutil>dmd -profile -odc:\dmd\projects\bsdutil\obj
-ofBSDUTIL.D
 LL bsdutil.d demangle.d bsdutil.def
 bsdutil.d(110): Error: undefined identifier _arguments
 bsdutil.d(110): Error: _arguments must be an array or pointer type, not 
 int



Ur typesafe variadic function, ur doin it wrong.

You declare the typesafe variadic param as so:

uint BinaryOrPlus(uint[] vals...)

then just use vals.

Typesafe variadic params are just sugar for passing an array literal.  In 
fact you can also pass an array reference in place of a list of params.

To that end, unless 4GL supports passing D arrays, you're going to have to 
do something else.
Feb 08 2008
parent reply Bjoern <nanali nospam-wanadoo.fr> writes:
Jarrett Billingsley schrieb:

 "Bjoern" <nanali nospam-wanadoo.fr> wrote in message 
 news:foi37b$19vv$1 digitalmars.com...
 

 export extern (Windows) uint BinaryOrPlus(uint...)
 {
   uint result = _arguments[0];
   for (int i = 1; i < _arguments.length; i++)
   {
      result |= _arguments[i];
   }
   return result;
 }

 Unfortunately Error msg is :

 C:\dmd\projects\bsdutil>dmd -profile -odc:\dmd\projects\bsdutil\obj
-ofBSDUTIL.D
 LL bsdutil.d demangle.d bsdutil.def
 bsdutil.d(110): Error: undefined identifier _arguments
 bsdutil.d(110): Error: _arguments must be an array or pointer type, not 
 int



 Ur typesafe variadic function, ur doin it wrong.
 
 You declare the typesafe variadic param as so:
 
 uint BinaryOrPlus(uint[] vals...)
 
 then just use vals.



How to iterate over vals  ?


 
 Typesafe variadic params are just sugar for passing an array literal.  In 
 fact you can also pass an array reference in place of a list of params.
 
 To that end, unless 4GL supports passing D arrays, you're going to have to 
 do something else. 



I can only use C style fixed arrays but this will end in code like
arr is fixed array on 3 uint = [WS_HONK, WS_TONK, WS_ITCH]
so, no win for me

 
 



okay let's forget about "typesafe" I can manage this in 4GL code, 
however following the D guidelines this should work :

export extern (Windows) uint BinaryOrPlus(uint firstarg, ...)
{
   uint result = firstarg; //_arguments[0];
   for (int i = 1; i < _arguments.length; i++)
   {
      result |= *cast(uint *)_argptr;
         _argptr += uint.sizeof;
   }
   return result;
}

In fact it don't work and it is looks dirty. they question here is ; 
what is the matter with _arguments /// using Tango

Thanks for spending your time
Bjoern
Feb 08 2008
parent "Jarrett Billingsley" <kb3ctd2 yahoo.com> writes:
"Bjoern" <nanali nospam-wanadoo.fr> wrote in message 
news:foic4a$1vk7$1 digitalmars.com...


 You declare the typesafe variadic param as so:

 uint BinaryOrPlus(uint[] vals...)

 then just use vals.



 How to iterate over vals  ?



.. Uh, seriously?

It's an array.


 okay let's forget about "typesafe" I can manage this in 4GL code, however 
 following the D guidelines this should work :

 export extern (Windows) uint BinaryOrPlus(uint firstarg, ...)
 {
   uint result = firstarg; //_arguments[0];
   for (int i = 1; i < _arguments.length; i++)
   {
      result |= *cast(uint *)_argptr;
         _argptr += uint.sizeof;
   }
   return result;
 }

 In fact it don't work and it is looks dirty. they question here is ; what 
 is the matter with _arguments /// using Tango



extern(Windows) variadic functions don't have an _arguments parameter, only 
extern(D) variadic functions do.

According to the spec, extern(C) (and maybe Windows, it doesn't say) are 
supposed to have an _argptr parameter but it doesn't seem to work :\

So, since you're basically writing a C function, you have to do it the C 
way: with va_start and the like.

In phobos it's in std.c.stdarg, and in Tango, tango.stdc.stdarg.  You'd do 
something like:

export extern(Windows) uint BinOr(uint firstarg, ...)
{
    va_list args;
    va_start(args, firstarg);

    // it's up to you to figure out the end of the list!
    // isn't that fun?

    va_end(args);
}

Lastly -- why _are_ you using this bizarre language anyway?
Feb 09 2008