The other day, I started a project to eventually replace the backend of Kirsle.net with a Go program instead of the current Python one (Rophako). It will support a similar feature set (being modular with even the core functionality, like user accounts and web blogs, being served by built-in "plugins" and allowing users to extend it with their own plugins).
The plugin system will support both compile-time plugins (your
main.go imports and registers all the plugins you need when compiling the binary), and run-time plugins using Go's plugins from *.so files support.
This post will focus on the former, compile-time plugins, and how I ran into a cyclic dependency issue and worked around it.
Recently, I was developing a Python/Flask app to implement Web Hooks for a third-party API that I was working with. The API recommended the use of ngrok during local development so that the server running on your local computer could be accessed publicly over the Internet (so that their API could reach yours).
ngrok is cool and all, but for their free plan they randomize the subdomain they give you every time you start the program. This meant I always had to log into my API account and change my Web Hook URL each day.
What ngrok is doing is nothing new: I've written about using SSH to forward ports between machines, and figured it should be easy enough for me to configure a subdomain on my own server that forwards traffic to another port that I could open when I need to.
The most recent feature I added to my website's CMS: multi-file uploads for the photo albums. I've been wanting to get around to this for a while so I can actually upload photo albums in bulk and make better use of that feature on my site.
So I did some research and found some bits of example code here and there, and put together a pure HTML5 multiple-file uploader with progress bar. No Flash, no Java, no Internet Explorer 9 or lower.
A lot of the existing bits of code I found out there weren't quite written in a way that was useful for my purposes. Their code tended to run the upload immediately after getting ahold of the files, i.e. they'd set up an HTML5 drag-and-drop spot and/or a multiple-file
On my CMS I wanted to hold off on the uploading, because there's other form elements to take care of too, i.e. what album to put the pictures into or to apply a caption to them all. So I set up handlers for my file input box and drag-drop site to just put all the
File objects into an array and wait for the submit button to be pushed.
So in my implementation, all the pictures are uploaded at once to the back-end, and there's only one progress bar (for the entire upload). It's possible to have one upload event per individual file, and therefore get progress bars on a file-by-file basis, but this didn't fit into my existing code structure.
POSTed to directly, i.e. for users with NoScript enabled. In both cases, they hit the
/photos/upload on the server to send the form and images.
When the Ajax is the one doing it, it adds an extra
Anyway, I threw together a quick Python/Flask app to mess with this stuff and figure it all out so I didn't have to worry about trying to wrangle existing code into doing something new. I have it hosted on Github here: https://github.com/kirsle/flask-multi-upload
Time for another Minecraft tutorial using command blocks to do something pretty neat using the vanilla version of the game (no plugins necessary). I used Minecraft version 1.7.9.
In this mini tutorial, I'm showing off how I created a "Limbo Dimension" that players are sent to after death, where they must remain for 60 minutes before being respawned in the overworld again.
This is a trick I picked up somewhere from /r/Minecraft that lets you implement anti-griefing on a 100% vanilla Minecraft server.
It requires you to have operator rights on the server, and it involves command blocks. Give yourself a command block by typing the command
/give your_name command_block, and place it somewhere in the center of the area you don't want being griefed. I usually will hide it just below the ground, or in a small hidden-away room in the middle of a building or something. Right-click it, and enter this command:
effect @a[m=0,r=36] 4 2 5 trueWhen activated, this command will apply a status effect to all Survival Mode players (
m=0), within a radius of 36 blocks from the command block (
r=36). The effect will be Mining Fatigue (effect ID
5, which will last for
2seconds. The word "true" at the end will hide the particle effects (supported in Minecraft 1.8+; for older versions, remove the word "true" from the command). See Status effect on the Minecraft wiki for details.
Mining Fatigue slows down the player's mining speed by 20% per level, so at level 5 your speed is slowed by 100%. What this basically means is that nobody can break anything while under Mining Fatigue 5. You can't even break a dandelion using a diamond axe. It makes the area completely grief-proof.
Adjust the radius to however large you think you'll need to cover the entire area you want protected. If the area is very large (i.e. so that the command block might end up being unloaded from memory when its chunk goes away), you'll need multiple command blocks positioned around the area to make sure the Mining Fatigue is still in effect.
Anyway, now you just need to hook up the command block to a redstone clock so that it's triggered repeatedly. My favorite is to just use a hopper clock. A comparator clock has too fast of a pulse and the command block will never be executed.
With a hopper clock, just place two hoppers that connect to each other. For example, place a normal block like stone, and then with a hopper, right-click on the side of the stone block so the bottom of the hopper connects to the side. Remove the stone block, go to the side where it used to be, and hold down Shift and right-click the hopper to attach the second one.
Edit for 1.8: It seems the timing has been changed in hoppers on Minecraft 1.8, and a two-hopper clock is "too fast" and won't trigger the command block repeatedly (it will trigger it one time and then never again). Instead of using 2 hoppers that feed into each other, you can use 4 hoppers that feed in a circle, each one connecting to the next one. This slows down the rate that the command block gets executed by 50% but it still works in Minecraft 1.8.
Put a single item into one of the hoppers. If it worked, the item should disappear from the hopper's GUI and then reappear shortly after; the item is being passed back and forth between the hoppers. Now, pick one hopper and put a comparator and then a repeater next to it. Whenever this hopper has the item, the comparator will get a signal and the repeater will amplify it. And there you go. Here's a screenshot of the full setup:
What about creepers and endermen?
Even if you prevent players from destroying blocks manually, they could still lure a creeper in and cause it to explode and damage the nearby blocks. In Minecraft 1.8+ you can select entities by type using command blocks, so you may wanna add some more command blocks to killl any creepers or endermen that get too close (the endermen are optional, but if your build involves a lot of natural blocks like dirt and sand you may wanna keep them away too):
You may also be able to do the same for the `PrimedTnt` entity but that may be trickier considering the speed at which TNT can be launched. You'd need a particularly fast redstone clock to keep up.