Python: Trick of the Day

Let's say you have a function that makes use of a global. (Pretend for a moment that global isn't a dirty word.) Let's say you want to define that global within that function, but only if it doesn't already exist. You can use "globals()" and "setdefault" together in the following, fun one-liner:

x = globals().setdefault("x", 0)

This will get the value of the global x. If x didn't already exist, it'll be initialized to 0.

Comments

Brantley Harris said…

Nice!

Globals in Python are really just module-level variables. Nothin' wrong with that.

5:13 PM

Anonymous said…

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10:14 PM

Drawing Sierpinski's Triangle in Minecraft Using Python

In his keynote at PyCon, Eben Upton, the Executive Director of the Rasberry Pi Foundation, mentioned that not only has Minecraft been ported to the Rasberry Pi, but you can even control it with Python. Since four of my kids are avid Minecraft fans, I figured this might be a good time to teach them to program using Python. So I started yesterday with the goal of programming something cool for Minecraft and then showing it off at the San Francisco Python Meetup in the evening.

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I've been reading Dreaming in Code lately, and I really like it. If you're not a dreamer, you may safely skip the rest of this post ;)

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Now, I'm sure that many of these ideas have already been envisioned within Tunes.org, LLVM, Microsoft's Singularity project, or in some other place that I haven't managed to discover or fully read, but I'm going to blog them anyway.

Rather than wax philosophical, let me just dump out some ideas:Start with Minix 3. It's a new microkernel, and it's meant for real use, unlike the original Minix. "This new OS is extremely small, with the part that runs in kernel mode under 4000 lines of executable code." I bet it&…

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