AKMA’s Random Thoughts

Well, let's see. If I was going to give a sermon this weekend, it would probably be on the idea of the newcomer. About how we can tell whether that knocking at the door is a barbarian at the gates or a savior on a path of palms, and when we have to trustfully (I could say 'faithfully', I suppose) just go ahead and open the door. I've been thinking about this question after reading Ernest Hebert's novel of rural New Hampshire The Dogs of March, in which residents recent, long-time, and very-long-time grapple for control of a town and its values. And, of course, there's a wealth of verses about junk car visibility ordinances in the Bible--mostly in the Book of Earl, if I recall correctly, which I seldom do.

It may not be much of a sermon, but perhaps you'd enjoy the novel anyway.

Mark and I were tossing these texts around, as he's preaching this Sunday, too. Ramblings of rookie curate and greenhorn seminarian, for what they're worth...

We were musing, as you say, over the apocolyptic tones; and the message (notably in Hebrews) that Being a Christian Ain't Easy, that there's no earthly bed of roses guaranteed (modern televangelistic salesmanship to the contrary). And how sometimes, it's even harder: when we are called to speak, rather than to be silent; to love, rather than to be indifferent; to live for Christ, rather than for oneself.

But easier is not the same as better, is it?

(I have no idea if any of this would be applicable to your parish world tomorrow; but that's where our discussion led).

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.

We can see an example of this in our code we've written so far. In each function's block, we declare variables that hold our data. When each function ends, the variables within are disposed of, and the space they were using is given back to the computer to use. The variables live in the blocks of conditionals and loops we write, but they don't cascade into functions we call, because those aren't sub-blocks, but different sections of code entirely. Every variable we've written has a well-defined lifetime of one function.

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.

Let's take a moment to reexamine that. What we've done here is create two variables. The first variable is in the Heap, and we're storing data in it. That's the obvious one. But the second variable is a pointer to the first one, and it exists on the Stack. This variable is the one that's really called favoriteNumber, and it's the one we're working with. It is important to remember that there are now two parts to our simple variable, one of which exists in each world. This kind of division is common is C, but omnipresent in Cocoa. When you start making objects, Cocoa makes them all in the Heap because the Stack isn't big enough to hold them. In Cocoa, you deal with objects through pointers everywhere and are actually forbidden from dealing with them directly.

We can see an example of this in our code we've written so far. In each function's block, we declare variables that hold our data. When each function ends, the variables within are disposed of, and the space they were using is given back to the computer to use. The variables live in the blocks of conditionals and loops we write, but they don't cascade into functions we call, because those aren't sub-blocks, but different sections of code entirely. Every variable we've written has a well-defined lifetime of one function.