AKMA’s Random Thoughts

You know, this photo in the midst of a strongly spiritual weblog does have a rather spooky look to it. But I assume this was you being made up for the interview?

(please say yes)

Again I suggest that we get a make-up artist for the sacristy at Seabury.

no offense, but you look vaguely like a puppy in the photo.

Hey, what happened to the ponytail?

Shelley: Yes — I’m not having a mystical revelation.

Tripp: Talk to Dean Meyers.

Paul: Woof!

Tim: The ponytail is like, so 90’s!

Being able to understand that basic idea opens up a vast amount of power that can be used and abused, and we're going to look at a few of the better ways to deal with it in this article.

But variables get one benefit people do not

Since the Heap has no definite rules as to where it will create space for you, there must be some way of figuring out where your new space is. And the answer is, simply enough, addressing. When you create new space in the heap to hold your data, you get back an address that tells you where your new space is, so your bits can move in. This address is called a Pointer, and it's really just a hexadecimal number that points to a location in the heap. Since it's really just a number, it can be stored quite nicely into a variable.

When Batman went home at the end of a night spent fighting crime, he put on a suit and tie and became Bruce Wayne. When Clark Kent saw a news story getting too hot, a phone booth hid his change into Superman. When you're programming, all the variables you juggle around are doing similar tricks as they present one face to you and a totally different one to the machine.

For this program, it was a bit of overkill. It's a lot of overkill, actually. There's usually no need to store integers in the Heap, unless you're making a whole lot of them. But even in this simpler form, it gives us a little bit more flexibility than we had before, in that we can create and destroy variables as we need, without having to worry about the Stack. It also demonstrates a new variable type, the pointer, which you will use extensively throughout your programming. And it is a pattern that is ubiquitous in Cocoa, so it is a pattern you will need to understand, even though Cocoa makes it much more transparent than it is here.

But some variables are immortal. These variables are declared outside of blocks, outside of functions. Since they don't have a block to exist in they are called global variables (as opposed to local variables), because they exist in all blocks, everywhere, and they never go out of scope. Although powerful, these kinds of variables are generally frowned upon because they encourage bad program design.