Monday, 29 July 2013

It's a trap

There was this bug I wanted to fix. When you looked at a trap it was telling the name of the trap, like poison gas trap. But how could the player know that before stepping onto it? I had to fix that by adding "identified" flag in Trap class and returning a generic name like "pressure plate" if the trap was not identified.

Following the new std::string message style I wanted to make the generic name const. In C++ const is a immutable variable, something that can't be changed once it's set. The problem was that Get_Name() returned plain char* and it is a virtual function of 15 total game object classes. So there was some of that good old const correctness when I changed all those routines to return const char*. It wasn't that bad and at least now it's done.

I've had my personal issues with const correctness, because it's sometimes difficult to grasp the concept of const. It's not that I don't use const. I'm using it almost always when setting up local pre-calculated variables etc. because it really eliminates one way (a subtle one) to create bugs. But when using const in data it can create a long chain where everything else must also be const. However lately I've started to use const in my framework routines etc. so it's becoming easier to be correct.

The bug was fixed, but I started to think about how messages work in Creature class and I guess there are some things to consider. Sometimes messages are constructed for all creatures when in fact only player can generate the message. The message output can be limited to the player, but the message itself can be constructed for all actors and it can slow down the game when there is a large number of creatures in the level. It's something I have to remember when I get into details of the Creature class routines.

1 comment:

  1. Oh C++

    Silly little things like handling const properly are part of the reason I don't like the language. In reality though, all languages have their quirks and there will always be bugs.