• Moritz Warning (12/12) Jun 28 2008 Hello,
• Moritz Warning (3/3) Jun 28 2008 Ok, nvm. :)
• Moritz Warning (6/10) Jun 28 2008 ok, a problem remains.
• Jason House (3/17) Jun 29 2008 What about doing the reverse... at runtime cast to void* when doing the
• Moritz Warning (3/22) Jun 29 2008 I did that already.
• Mike (9/11) Jun 28 2008 union
• Moritz Warning (4/15) Jun 28 2008 Would work probably.

Moritz Warning <moritzwarning web.de> writes:

Hello,

I wrote a container that relies on treating two different values in a 
special way (they are used as some kind of flag).
For a container of integers, I just use 0 and 1 as special elements.
Those special entries are for internal use only.

The problem comes when I extend the container for reference types.
Instead of 0 I use null, but for 1 the trouble begins.

Is it possible to circumvent the type system and convert an integer to a 
pointer or class type? They won't ever be dereferenced, of course.

Many would probably think that this is the wrong way anyway,
but I try to avoid memory usage that way and to increase speed.

Introducing special workarounds also make the code more complicated.

Moritz Warning <moritzwarning web.de> writes:

Ok, nvm. :)

void* p = cast(void*) 1;
A a = cast(A) p;

Moritz Warning <moritzwarning web.de> writes:

On Sun, 29 Jun 2008 01:56:22 +0000, Moritz Warning wrote:

 Ok, nvm. :)
 
 void* p = cast(void*) 1;
 A a = cast(A) p;

ok, a problem remains.
How to do this at compile time?:

static const T first = cast(T) cast(void*) 0;
static const T second = cast(T) cast(void*) 1;

..doesn't work.

Jason House <jason.james.house gmail.com> writes:

Moritz Warning wrote:

 On Sun, 29 Jun 2008 01:56:22 +0000, Moritz Warning wrote:
 
 Ok, nvm. :)
 
 void* p = cast(void*) 1;
 A a = cast(A) p;

 
 ok, a problem remains.
 How to do this at compile time?:
 
 static const T first = cast(T) cast(void*) 0;
 static const T second = cast(T) cast(void*) 1;
 
 ..doesn't work.

What about doing the reverse... at runtime cast to void* when doing the
comparison.  I think casting to void* is free

Moritz Warning <moritzwarning web.de> writes:

On Sun, 29 Jun 2008 18:27:18 -0400, Jason House wrote:

 Moritz Warning wrote:
 
 On Sun, 29 Jun 2008 01:56:22 +0000, Moritz Warning wrote:
 
 Ok, nvm. :)
 
 void* p = cast(void*) 1;
 A a = cast(A) p;

 
 ok, a problem remains.
 How to do this at compile time?:
 
 static const T first = cast(T) cast(void*) 0; static const T second =
 cast(T) cast(void*) 1;
 
 ..doesn't work.

 
 What about doing the reverse... at runtime cast to void* when doing the
 comparison.  I think casting to void* is free

I did that already.
Thanks for the suggestion.

Mike <vertex gmx.at> writes:

On Sun, 29 Jun 2008 03:35:03 +0200, Moritz Warning <moritzwarning web.de>  
wrote:

 Is it possible to circumvent the type system and convert an integer to a
 pointer or class type? They won't ever be dereferenced, of course.

union
{
     int integer;
     void *pointer;
}


-- 
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Moritz Warning <moritzwarning web.de> writes:

On Sun, 29 Jun 2008 04:05:02 +0200, Mike wrote:

 On Sun, 29 Jun 2008 03:35:03 +0200, Moritz Warning
 <moritzwarning web.de> wrote:
 
 Is it possible to circumvent the type system and convert an integer to
 a pointer or class type? They won't ever be dereferenced, of course.

 
 union
 {
      int integer;
      void *pointer;
 }

Would work probably.
But I found another solution using a static and alias to fit in two base 
types quite nicely. (size_t and void*)