What does "first class" mean?

[Samuel A. Falvo II]

In article <slrn8gkalp.3bk.neelk at brick.cswv.com>, Neel Krishnaswami wrote:
>In Pascal or C, for example, you can't write a procedure that creates
>a function and returns it to its callers, whereas in Scheme or Python
>this is trivial.

This isn't *strictly* true.  The following code, for x86 processors, returns
a function that does nothing:

typedef void NoOp();

NoOp *GenerateNoOpFunction( void )
{
   char *buf;
   
   buf = malloc( 2 );
   if( buf != NULL )
   {
      buf[0] = 0x90;	/* NOP instruction; for demonstration */
      buf[1] = 0xC3;	/* RET instruction */
   }
   
   return buf;
}

Sorry, I couldn't resist.  :-)

Seriously, though, this technique has been used in various graphics drivers,
most often with software-only blit engines (where speed is critical).
They'd basically act as dedicated compilers.  Windows 95's stock VGA device
driver does this, if memory serves me correctly.

-- 
KC5TJA/6, DM13, QRP-L #1447
Samuel A. Falvo II
Oceanside, CA