Phil Miller philmill

Homebrew Upgrade of Rabbitmq Gotcha

If you recieve something like {could_not_start,rabbit,{previous_upgrade_failed,{rabbit,start,[normal,[]]}}}, searching for could_not_start didn't provide me with much help.

Remove previous mnesia contents

For rabbitmq: stable 3.5.3 this is located at /usr/local/var/lib/rabbitmq/mnesia/.

Simply rm -rf * to remove all of it's contents.

3 Main Principles

Single Immutable State Tree

All application state is contained in a single object tree which cannot be modified directly.

Actions

Actions are used to modify the app state tree. They're objects which describe changes. They only require a type key with other info to describe the change. Any data that will be represented by the app tree will get there via actions regardless of source (UX || Network).

{ type: "ADD_ITEM",
 index: 1,

	// inspect an element for events (jquery <= 1.7)
	$("SELECTOR").data("events");

	// not selector
	$( "input:not(:checked)" )

	// Falsey
	0, NaN, ""

	// Automatic Type Conversion!!!
	console.log(8 * null)
	//> 0
	console.log("5" - 1)
	//> 4
	console.log("5" + 1)
	//> 51

	begin
	# something which might raise an exception
	rescue SomeExceptionClass => some_variable
	# code that deals with some exception
	rescue SomeOtherException => some_other_variable
	# code that deals with some other exception
	else
	# code that runs only if no exception was raised
	ensure
	# ensure that this code always runs, no matter what

	# jQuery(function($){
	# });

	# can be re-written as
	jQuery ($) ->
	console.log 'stuff'
	# or if jQuery is only one useing $
	$ ->
	console.log 'stuff'