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runtime type casting

Started by steve coward Nov 30, 2001 at 5:50 PM 4 replies 350+ views

Original Post

Nov 30, 2001 at 5:50 PM

I am developing a 2D game based on Red Alert game. I have a tank class and an infantry class, among others. I want to be able to pass into a subroutine a pointer to either a instance of the tank class or an instance of the infantry class, and possibly a flag telling which type. How can the subroutine determine which type of class the pointer points to? I would like to avoid using a case/if statement which duplicates large portions of the subroutine since this is not much different than just having separate subroutines. Something like this?? - void func1(CGenericUnit* pGenericUnit, int type) { if (type == TANK) { CTankUnit* pUnit; pUnit = (CGroundUnit*)pGenericUnit; } else if (type == INFANTRY) { CInfantryUnit* pUnit; pUnit = (CInfantryUnit*)pGenericUnit; } // now use pUnit freely except locality is broken pUnit->setLocation(location); // etc } thanks in advance for any help you are able to provide, steve coward

Null and Void

163

Null and Void

Nov 30, 2001 at 6:05 PM

Assuming I understand what you''re asking/saying, wouldn''t virtual functions work fine?

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Shannon Barber

Mod

368

Shannon Barber

Nov 30, 2001 at 9:54 PM

...using a dynamic_cast<>

Odds are good there''s BSA if you need a dynamic cast.

Magmai Kai Holmlor
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Void

129

Void

Dec 1, 2001 at 7:41 AM

You need double dispatching. Look at Scott Meyer''s More Effective C++ or search www.cuj.com

Kylotan

Mod

3,487

Kylotan

Dec 2, 2001 at 11:42 AM

As far as I can tell, this is a simple use of virtual functions:

  
class CGenericUnit
{
    virtual setLocation(LocationType newloc);
};

class CGroundUnit : public CGenericUnit
{
    virtual setLocation(LocationType newloc)
    { // CGroundUnit specific stuff }

};

class CGenericUnit : public CGenericUnit
{
    virtual setLocation(LocationType newloc)
    { // CInfantryUnit specific stuff }

};

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