Jin Kwon onacit

Fundamentals: why state machines?

States. The final frontier. These are the voyages of an enterprising developer. Her eternal mission: to explore strange new techniques, to seek out better ways to engineer for mental models and new design patterns. To boldly go where a few awesome devs have gone before.

So you’ve found our poignant guide to SCXML and surely you’re wondering “Why should I want to go out of my way to use formal state machines?” or something like that. Hopefully this introduction addresses that kind of question.

An example: Nancy’s RPG

The problem

To remove a submodule you need to:

Delete the relevant section from the .gitmodules file.
Stage the .gitmodules changes git add .gitmodules
Delete the relevant section from .git/config.
Run git rm --cached path_to_submodule (no trailing slash).
Run rm -rf .git/modules/path_to_submodule (no trailing slash).
Commit git commit -m "Removed submodule "
Delete the now untracked submodule files rm -rf path_to_submodule

It seems that it does not matter what timezone is on the server as long as you have the time set right for the current timezone, know the timezone of the datetime columns that you store, and are aware of the issues with daylight savings time.

On the other hand if you have control of the timezones of the servers you work with then you can have everything set to UTC internally and never worry about timezones and DST.

Here are some notes I collected of how to work with timezones as a form of cheatsheet for myself and others which might influence what timezone the person will choose for his/her server and how he/she will store date and time.

MySQL Timezone Cheatsheet

Prereq:

apt-get install zsh
apt-get install git-core

Getting zsh to work in ubuntu is weird, since sh does not understand the source command. So, you do this to install zsh

wget https://github.com/robbyrussell/oh-my-zsh/raw/master/tools/install.sh -O - | zsh

	/* llist.c
	* Generic Linked List implementation
	*/

	#include <stdlib.h>
	#include <stdio.h>
	#include "llist.h"

	llist llist_create(void new_data)
	{

	#delete all the remote tags with the pattern your looking for, ie. DEV-
	git tag \| grep <pattern> \| xargs -n 1 -i% git push origin :refs/tags/%
	#delete all your local tags
	git tag \| xargs -n 1 -i% git tag -d %
	#fetch the remote tags which still remain
	git fetch

	@Entity
	public class Parent {

	@Id
	private Long id;

	@OneToOne(fetch = FetchType.LAZY)
	@NotFound(action=NotFoundAction.IGNORE) // You don't need this annotation if you use the approach below
	private Son son;

	// This is the source code for Integer.bitCount() for Java 1.5+
	// <http://www.docjar.com/html/api/java/lang/Integer.java.html> line 1132

	public static int bitCount(int i) {
	i = i - ((i >>> 1) & 0x55555555);
	i = (i & 0x33333333) + ((i >>> 2) & 0x33333333);
	i = (i + (i >>> 4)) & 0x0f0f0f0f;
	i = i + (i >>> 8);
	i = i + (i >>> 16);
	return i & 0x3f;