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Author Topic: Polymorphism Problem  (Read 39 times)

MacroHard

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Polymorphism Problem
« on: February 22, 2005, 03:58:00 AM »
Seems like the compiler sees the declaration of Enemy::Burn() but it can't find the definition for it.  Are you sure it's really defined someplace (in Enemy_Class.cpp or wherever) ?
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Peeveen

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Polymorphism Problem
« Reply #1 on: February 22, 2005, 08:26:00 AM »
Do you still have implementations for the Enemy::Move() and Enemy::Burn() methods?

If not, I would guess that somewhere in your code you've got a method that creates an instance of Enemy, and now that Enemy is an abstract class, that's not valid.
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Hexstr

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Polymorphism Problem
« Reply #2 on: February 22, 2005, 12:32:00 PM »
Yes Peeveen is correct.  You can't create an instance of a class that has abstract methods.  In other words you need to have an implementation of Enemy::Burn() even if the code is { return; }.
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Ecrofirt

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Polymorphism Problem
« Reply #3 on: February 22, 2005, 01:12:00 PM »
ah, thanks for the help guys. I'll implement this now, and see if it works. I hope it does, because I've been pulling my hair out over this.
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Ecrofirt

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Polymorphism Problem
« Reply #4 on: February 22, 2005, 01:25:00 PM »
Awesome guys, it worked.

I hadn't thought about the abstract class thing, although looking on it now it was obvious. I know you can't creat objects that are just from an abstract class.

The basic way I've got my enemy generation is:
Enemy *NewEnemy;

NewEnemy=new WhateverType

vEnemies.push_back(NewEnemy);

so I should have caught that right off the bat.

Thanks for the help!
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