Re: c++ const aggregate vs constructor

[Xiaolong Tang <txltamu at gmail dot com>]

On Jun 25, 2007, at 4:59 PM, Kevin Yohe wrote:

> Hi,
>
> I am trying to define a constant table that can be initialized at
> compile-time and linked into ROM.  I had envisioned two ways of  
> defining
> this; either
>
> struct sAggregate
> {
> 	int m0;
> 	int m1;
> 	int m2;
> 	int m3;
> };
>
> const sAggregate table1[] =
> {	{ 0, 0, 0, 0 },
> 	{ 1, 1, 1, 1 },
> 	{ 2, 2, 2, 2 },
> 	{ 3, 3, 3, 3 }
> };

As a POD type, this initialization is called static initialization  
(from constants) , which shall be
performed at compile time (most implementation).

> or
>
> struct sConstruct
> {
> 	int m0;
> 	int m1;
> 	int m2;
> 	int m3;
>
> 	sConstruct( a0, a1, a2, a3 )
> 		: m0(a0), m1(a1), m2(a2), m3(a3)
> 		{};
> };
>
> const sConstruct table2[] =
> {	sConstruct( 0, 0, 0, 0 ),
> 	sConstruct( 1, 1, 1, 1 ),
> 	sConstruct( 2, 2, 2, 2 ),
> 	sConstruct( 3, 3, 3, 3 )
> };

On the contrary, this is not a POD type (user_declared constructors)
, and is dynamic initialization happening at run time.
'cause this direct initialization might involve constructor resolution.

Am I rit?

>