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The other day I was thinking wayyyy too hard about nothing in particular, and I thought about the simple ambiguity of naming ourselves.

From the movie Orgasmo:

Maxxx Orbison:
What’s your name, again?
Sancho:
I am Sancho.
Maxxx Orbison:
Look, I get a lot of people auditioning all the time. What makes you think that you’d be good enough for porno?
Sancho:
I am Sancho.
Maxxx Orbison:
Great… but what do you do?
Sancho:
What do I do? I am Sancho.
Maxxx Orbison:
And…?
Sancho:
And there are many Jeffs in the world, and many Toms as well. But I… am Sancho.
Maxxx Orbison:
And…?
Sancho:
Are you Sancho? No you are not. Neither is Scott Baio Sancho. Frank Gifford is not Sancho. But I…
Maxxx Orbison:
You… are Sancho!
Sancho:
That’s right.
Maxxx Orbison:
Okay, you’re hired.

In a nutshell, Sancho is stating something more abstract than just his name. I can say “I am Tom Barta”, but typically I just mean “My name is Tom Barta.” This guy isn’t just named Sancho, he is Sancho, and there is no other.

Think about it: what do you really mean if you go up to a stranger and ask, “Who are you?” The answer could be “John”, “a businessman”, “your neighbor”, or “a pround Republican”. Similarly, if you approach someone and say “Hi, I am John,” I can imagine it would take a tiny bit more processing than saying “Hi, my name is John.” If your name is rare (like Moon Unit or Apple), it’s even more important to remove any ambiguity. “I am Apple” sounds like nonsense or pidgin.

There’s a Nerd-Tangent Hidden in Every Real-Life Thought

There is a parallel between this and programming. The advent of object-oriented programming has popularized the notion of “object identity” versus “object equality”. I can have two objects sitting in memory with identical data. Sometimes, that’s just a programming error, and the same object has been copied unnecessarily (this happens frequently with caching or persistent systems). Sometimes, the two objects genuinely are different. How can I tell if one is just an alias, or if they are logically distinct?

It depends, of course. If I am looking at Value Objects, there’s generally not a reason to distinguish them by identity. The color Red is always Red, even if I have two Reds. However, with Entities, identity is of utmost importance. Two John Smiths in a customer database represent different people. Another way to think about it is in the context of the Flyweight pattern. The two Reds could be replaced with a flyweight without affecting the program. However, the John Smiths couldn’t.

Enter Programming Languages

Of course, programming languages that use objects must have some way of distinguishing object identity from object equality.

Language Identity Equality
C, C++ &a == &b a == b
Java Anyone care to fill this one in for me? I’m unaware of the semantics of == and equals().
PHP nothing! a == b (coerce types to match) or a === b (check types)
Python a is b a == b

Whoops! Looks like PHP doesn’t even have object identity! I’d like for someone to be able to refute this, but I haven’t been able to figure it out. PHP documentation claims === means identical and == means equal, but that certainly doesn’t match the notion of object identity I just explained. Sadly, this essentially means that object identity will never truly work in PHP. Instead, we are left with “equal” and “more equal”.

Does it Matter?

In the big picture, I don’t think it hurts PHP programmers to lose object identity. Most PHP applications are business-logic interfaces sitting on top of relational databases. What’s special about the RDBMS in this context? Well, object identity doesn’t exist. I know Postgres has oid and there are probably others, but using them for general applications seems to be unfavorable. In a database table, objects (tuples/records/rows) are identified by a primary key that disallows duplicates and frequently uses auto-incrementing integers. It’s a trivial solution, really, to just assign a number to everyone who walks in the door (until you run out of numbers, of course).

Since the database enforces this uniqueness, I know that two customers both named John Smith will at least have different customer IDs. Social Security, credit cards, university student IDs, and phone numbers all revolve around this notion of unique numeric identity. Consequently, almost any PHP application using a RDBMS can simply piggyback upon the database’s IDs and trivially state that === is now identical to ==.

Ok, so I should specify right off the bat my opinions about Java. I don’t like it, and many of its shortcomings more pronounced due to my experience with Python. I don’t like forcing a coupling between object and file hierarchies. I don’t like silly typing rules casting everything under the sun to an Object. I don’t understand the hype around JDBC: I expect my language to be bindable to my RDBMS, and I know that any advanced database programming will require sacrificing portability. I don’t like hearing advocates brag about the “write once, run anywhere” mantra when I know that not all JVMs (or JNI modules) are equal, or possible. I know Python’s not perfect either, but for the sake of my argument let me use it simply as a foil:

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I’m a PHP programmer. I’ve been using it since ’02 or ’03, and I’m very familiar with the language and “enough” of the packages to get by. Over the last few days, I’ve been taking another look at Django. I’ve looked through most of its code (it’s surprisingly small, I figured it would be bigger) and am trying to wrap my head around it to see how effectively I could actually use it. Most of the time, I’m really comparing it to how I’ve solved a particular problem with PHP in the past, or seeing what sort of Program Transformation is involved between what I’ve done and what the Django devs have done.

It’s really interesting to see a big common area (and makes me satisfied, that my design isn’t crazy), but then to see something that, for me, has worked with a single method, but that in their framework has been extracted out into their entire MiddleWare suite. Me likey.

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Pulling from Wikipedia:

function line(x0, x1, y0, y1)
     boolean steep := abs(y1 - y0) > abs(x1 - x0)
     if steep then
         swap(x0, y0)
         swap(x1, y1)
     if x0 > x1 then
         swap(x0, x1)
         swap(y0, y1)
     int deltax := x1 - x0
     int deltay := abs(y1 - y0)
     int error := 0
     int ystep
     int y := y0
     if y0 < y1 then ystep := 1 else ystep := -1
     for x from x0 to x1
         if steep then plot(y,x) else plot(x,y)
         error := error + deltay
         if 2×error ≥ deltax
             y := y + ystep
             error := error - deltax

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