Ken to the rescue :)
-Sniper
----- Original Message -----
From: "Ken Birdwell" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Tuesday, August 19, 2003 12:47 AM
Subject: RE: [hlcoders] Probably basic question
> The "MISC CODE" that looks like this:
>
> if ( !pOther->IsPlayer() )
> {
> return;
> }
>
> is very important. Casting towards the root of the hierarchy is generally
a
> safe thing to do in C++, whereas casting a base class pointer to a leaf
> class pointer is usually a very bad thing to do, you really don't know
what
> the actual class the pointer points to. The pOther pointer could just as
> easily point to a monster or a button or whatever rather than a player,
and
> none of the CBasePlayer member functions or data would be valid.
>
> The "correct" way to do this is to use RTTI - run time type information -
> which is a C++ thing where all the pointers have builtin functions to
> convert to their actual type and will return NULL if you try to do an
> invalid cast. Since HL doesn't use RTTI, it sometimes does a somewhat
hacky
> thing and the base class has a virtual IsPlayer() function that returns
> false on all leaf classes, except for CBasePlayer where it returns true.
> The slightly cleaner way to do it is the MyMonsterPointer() method,
another
> CBaseEntity virtual function that returns NULL for all classes, except for
> ones that derive from CBaseMonster, which is sort of a crude version of
> RTTI.
>
> -----Original Message-----
> From: Nick McLaren [mailto:[EMAIL PROTECTED]
> Sent: Monday, August 18, 2003 7:08 PM
> To: [EMAIL PROTECTED]
> Subject: [hlcoders] Probably basic question
>
>
>
> I asked this of a friend of mine, but I got the msg back due to his
> mailserver being down. Hoping perhaps the list could help me out. I'm
> aware that it is a bit of a newb question, but if you could help me out
> just the same, I guarantee I will never have the same question twice ;)
>
> It appears that the CBaseEntity pointer "pOther" gets converted to a
> CBasePlayer pointer in the code below. Is this only possible whereas the
> converted_to pointer-type is derived from the converted_from pointer-type?
> Also, are the parentheses on the right-hand side of the assignment
> necessary? Silly question I'm sure, but hey, I'm sure I get this 100% as I
> go. ;)
>
> void CBasePlayerItem::DefaultTouch( CBaseEntity *pOther )
> {
> /* MISC CODE HERE */
>
> CBasePlayer *pPlayer = (CBasePlayer *)pOther;
>
> /* MISC CODE HERE */
>
> ---------------------------
> Nick McLaren, CCNA, SCSA
> BattleLAN Technical Admin
> <[EMAIL PROTECTED]>
> http://www.battlelan.com/
> ---------------------------
>
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