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coding-styleconstantsprivate

When to use a private constant?

Is it right to use a private constant in the following situation:

Say I have a game with a lives variable and a startingLives variable. At the start of the game I set the lives variable to equal the startingLives variable. This is how I would normally do it:

private var lives:int = 0;
private var startingLives:int = 3;

private function startGame():void
{
   lives = startingLives;
}

(example code is ActionScript btw)

My question is - should this really be:

private var lives:int = 0;
private const STARTING_LIVES:int = 3;

private function startGame():void
{
  lives = STARTING_LIVES;
}

StartingLives seems unlikely to change at runtime, so should I use a const, and change back to a variable if it turns out not to be constant?

UPDATE: The consensus seems to be that this is a good use of a constant, but what about amdfan's suggestion that you may want to load the value in from a config file?

Solution

  • Put it in a constant named DEFAULT_STARTING_LIVES, but also have a variable named startingLives. For now, set startingLives = DEFAULT_STARTING_LIVES. Later, you can set startingLives based on a value from a configuration file. If the file has not been created or is not found, you have a back up.

    (thanks to Plinth for the expansion on my original answer.)