AKMA’s Random Thoughts

Sounds like a classic case of somebody did up the website in a fit of benevolent activity, and no arrangements were made to maintain it. Common enough thing -- look at textartisan. Better yet, don't.

Yeah, but they're Harvard. If you were important enough, you'd already know how to get in touch.

If only someone would invent some kind of protocol for this sort of thing. You could use it to access directories. And if it were lightweight, that would be even better!

Yes, I know LDAP isn't your beef here, but a single directory (with an LDAP interface) can often smooth some of these data maintenance issues....

Harvard, eh? The Global Blogging Centre calls?

Well, yes. Trevor and I thought it was a useful place to take news of the Disseminary. So I was writing around to local seminaries to see whether any of them want me to give a lecture on postmodernism, New Testament theology, technology, pedagogy, congregations, climbing trees during choir tours, or some other hot topic.

“Will Lecture For a Room”

Wow. There goes my alma mater! Harvard is notoriously decentralized -- you should have seen the Div School's site when I was there in the late 90s. You might try contacting the Office of Student Life or the Office of Ministerial Studies, if only because someone will actually answer the phone there. I have no idea how you'd get yourself invited to address the faculty, but these two offices would at least know how to put you in touch with the livelier students.

This is just the sort of task for which I find the telephone the appropriate tool. By the time I hit the second dead link, I'm either on the phone or saying, "Who cares?"

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.

This will allow us to use a few functions we didn't have access to before. These lines are still a mystery for now, but we'll explain them soon. Now we'll start working within the main function, where favoriteNumber is declared and used. The first thing we need to do is change how we declare the variable. Instead of

When compared to the Stack, the Heap is a simple thing to understand. All the memory that's left over is "in the Heap" (excepting some special cases and some reserve). There is little structure, but in return for this freedom of movement you must create and destroy any boundaries you need. And it is always possible that the heap might simply not have enough space for you.

This variable is then used in various lines of code, holding values given it by variable assignments along the way. In the course of its life, a variable can hold any number of variables and be used in any number of different ways. This flexibility is built on the precept we just learned: a variable is really just a block of bits, and those bits can hold whatever data the program needs to remember. They can hold enough data to remember an integer from as low as -2,147,483,647 up to 2,147,483,647 (one less than plus or minus 2^31). They can remember one character of writing. They can keep a decimal number with a huge amount of precision and a giant range. They can hold a time accurate to the second in a range of centuries. A few bits is not to be scoffed at.

Our next line looks familiar, except it starts with an asterisk. Again, we're using the star operator, and noting that this variable we're working with is a pointer. If we didn't, the computer would try to put the results of the right hand side of this statement (which evaluates to 6) into the pointer, overriding the value we need in the pointer, which is an address. This way, the computer knows to put the data not in the pointer, but into the place the pointer points to, which is in the Heap. So after this line, our int is living happily in the Heap, storing a value of 6, and our pointer tells us where that data is living.

This is another function provided for dealing with the heap. After you've created some space in the Heap, it's yours until you let go of it. When your program is done using it, you have to explicitly tell the computer that you don't need it anymore or the computer will save it for your future use (or until your program quits, when it knows you won't be needing the memory anymore). The call to simply tells the computer that you had this space, but you're done and the memory can be freed for use by something else later on.