RE: [GD-General] Overhead of RTTI

[Tom F. <to...@mu...>]

The easy, if rather messy and special-cased way, is to have a whole load of
functions like this all the way down the hierarchy:

virtual D3DTexture *MyCoolClass::GetD3DTexture ( void )
{
	// I'm not a D3DTexture you fool.
	return NULL;
}


...but then for the D3DTexture class it's

virtual D3DTexture *D3DTexture::GetD3DTexture ( void )
{
	return this;
}


Now sure, this pollutes your namespace with lots of GetMyFunkyClassName()
calls, but if that's all you need to do, it's robust and pretty easy to
understand, and doesn't require any RTTI support.


Tom Forsyth - Muckyfoot bloke and Microsoft MVP.

This email is the product of your deranged imagination,
and does not in any way imply existence of the author.

> -----Original Message-----
> From: Adrian Cearnau [mailto:ce...@ce...]
> Sent: 24 December 2002 13:26
> To: gam...@li...
> Subject: RE: [GD-General] Overhead of RTTI
> 
> 
> Hey,
> 
> It might be a bad design, but now that I've hit this problem, I'd also
> like to know why it happens and how much RTTI would *really* hurt. The
> class hierarchy in discussion has a base Obect class that has a name
> field and is virtually inherited by all the other classes in the
> hierarchy. Now I have a Texture class and a RenderTarget class (buth
> abstract), and in the implementation I have a (say) D3DTexture class
> that inherits both Texture and RenderTarget. The problem is that the
> RenderSystem class (the one that does the actual rendering) is pretty
> abstracted itself so it works with Textures and renderTargets. At some
> point I have to cast from Object to D3DTexture and there's where all
> hell brakes loose. I can't even cast from void * to 
> D3DTexture for that
> matter (well, the void * was initially a RenderTarget cast of
> D3DTexture, so yes, it is a whole madness). My bet is on 
> dynamic_cast or
> modifying the design (I'll probably choose the latter 
> eventually). Seems
> like hard abstraction would be way easier (and safer) with 
> RTTI enabled.
> 
> Thanks again,
> Adrian
> 
> -----Original Message-----
> From: gam...@li...
> [mailto:gam...@li...] On Behalf Of
> Tom Forsyth
> Sent: Tuesday, December 24, 2002 3:02 PM
> To: gam...@li...
> Subject: RE: [GD-General] Overhead of RTTI
> 
> It's usually far quicker and easier to code it yourself with a few
> helper
> functions, unless you actually need the full madness of RTTI.
> 
> Tom Forsyth - Muckyfoot bloke and Microsoft MVP.
> 
> This email is the product of your deranged imagination,
> and does not in any way imply existence of the author.
> 
> > -----Original Message-----
> > From: Adrian Cearnau [mailto:ce...@ce...]
> > Sent: 24 December 2002 12:50
> > To: gam...@li...
> > Subject: [GD-General] Overhead of RTTI
> > 
> > 
> > Hey everyone and merry X-Mas,
> > 
> > I'd like to know what the realistic overhead of enabling 
> RTTI in a C++
> > project is. Any opinions are welcome.
> > 
> > Thank you,
> > Adrian 'cearny' Cearnau
> 
> 
> 
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