Software Jam Sessions

Requiem for an operator

by Barry Warsaw

August 24, 2006



Summary

Guido kills <> in Python 3000. I am sad.


I heard the news today, oh boy This came in my email today: Author: guido.van.rossum Date: Thu Aug 24 05:53:23 2006 New Revision: 51538 Killed the <> operator. You must now use !=. I knew this day would come and yet I'm still sad. Having known Guido as long as I have, I also know that the likelihood he'll change his mind is about the same as Tim Peters eating anything other than Kung Pao chicken at an outing to China King restaurant. Still, I have a strong attachment to this operator so I'm returning to my blog in final remembrance and to once again explain why I like <> so much more than !=.

The argument for <> There are several reasons why I think <> is the better spelling for inequality. First, it's symmetrical and thus feels more closely related to its opposite, == for equality. Split either symbol vertically down the center and the two sides are mirrors of each other. The symmetry appeals to my eye. Second, <> stands out much better in code that already has == and = strewn about it. Maybe it's just me, but != is less visually distinct and my eye has a much harder time picking this out. It always has for C and Java, will so in Python code as well. Third and most importantly, <> is much easier to type (on a US keyboard at least). Think of the chording you have to do on a keyboard to type the two inequality operators. For <>, you hold the left shift down with your left pinkie, and then hit comma and period with the second and third fingers of your right hand. Quick and easy. With != I have to go through these movements: Hold right shift with my right pinkie and stretch my left ring finger all the way up to the 1 key

(or hold left shift with my pinkie while doing the same left ring finger stretch)

Let up on the shift key and stretch my right ring finger up to the = key at the opposite side of the keyboard There's no question that != is more awkward and slower to type. For me it's actually more painful too.

The argument for != Let's examine some of the arguments I've heard in favor of != instead of <>. First, TOOWTDI. This Python guiding principle stands for "There's Only One Way To Do It", and it's a principle that should be honored in this case too. Note however, this doesn't really argue in favor of either symbol -- it could just as appropriately be invoked for keeping <> and ditching !=. Another argument I've heard is that ! is a common character meaning "not" so != clearly means "not equal", while <> means "less than and greater than" and that's nonsensical. Well, != does not mean "not equal", it means "not an assignment" which is equally <wink> nonsensical. To literally mean "not equal" in Python, you'd have to write !== and no one's suggesting that! Third, I've heard that people coming from Java and C will be more comfortable with != than <> because that's what those languages use. This doesn't hold much water for me because any programmer worth their salt will understand that they have to make adjustments when they switch languages. How often do you type semicolons at the end of your Python statements? How often do you type colons at the end of your C conditionals? Yeah, me neither. Switching to <> when writing Python would actually be a good thing because it re-enforces the differences between Python and C/Java.

A Farewell Ultimately I believe this change was made because Guido simply likes != better than <> and thus it comes down to a religious argument. Since he's the BDFL and Python is his language, he gets to make these decisions. I don't have to like it, but I'll learn to live with it... eventually. In the meantime, here's my Ode to Inequality: One's not assignment but looks like such One's less and more but not by much One's within reach, an easy touch One looks like C, a useful crutch My fingers ache and stretch and pull To type the Py three inequal The end is near for symbol's duel I mourn the loss of diamond jewel The BDFL's made his choice To heed the call of Java's voice Some will cry and some rejoice And sed will lend a heavy hoist I'll linger then on Py two dot So I can have my equal not The angle brackets killed and caught In Guido's evil bang key plot So join me now in sweet revolt To Ruby, Perl, or Tcl bolt Naw, I'm just kidding truth be told But wouldn't that be quite a jolt? I'm just an old crumudgeon, moody Who thinks bang equals looks like doody So call me nuts or call me snooty I guess I'll eat my TOOWTDI fruity

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About the Blogger

Barry Warsaw has been developing software and playing music for more than 25 years. Since 1995 he has worked in Guido van Rossum's Pythonlabs team. He has been the lead developer of the JPython system, and is now the lead developer of GNU Mailman, a mailing list management system written primarily in Python. He's also a semi-professional musician. Python and the bass are his main axes. Music and software are both at their best when enjoyed, participated in, and shared by their enthusiastic fans and creators.

This weblog entry is Copyright © 2006 Barry Warsaw. All rights reserved.