RE: [GD-General] Overhead of RTTI

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

I would modify that to: "inheritance of multiple virtual classes is evil".
Multiple inheritance is just fine and dandy, as long as only one (or none)
of the parent classes is a virtual class.

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: Grills, Jeff [mailto:jg...@so...]
> Sent: 24 December 2002 13:55
> To: 'gam...@li...'
> Subject: RE: [GD-General] Overhead of RTTI
> 
> 
> 
> I didn't quite understand your email, so this comment may not 
> apply to your
> case.  You can't dynamic_cast<> from a void*.  You have to 
> have an object
> that has a virtual function in it, and you should be casting 
> from a base
> class of the desired target.
> 
> And, as a general rule, multiple inheritance is evil and 
> should be avoided.
> In fact, we've recently put a rule in place where any use of multiple
> inheritance requires a lead programmer's permission before 
> submitting to
> source control.
> 
> j
> 
> -----Original Message-----
> From: Adrian Cearnau [mailto:ce...@ce...]
> Sent: Tuesday, December 24, 2002 7:26 AM
> 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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