state_pattern | A Ruby state pattern implementation | Architecture library

The state pattern

itself is really nice pattern for implementing state machines because it allows to encapsulate state transitions logic in states themselves and adding a new state is actually becomes easier because you need to make changes only in relevant states.

But, it is usually avoided in description how should states be changed.

If you implement state change logic in Context then whole the point of pattern is missed, but if you implement state change logic in states, that means you need to set a new state in Context.

The most common way is to add the public method to Context SetState() and pass reference to Context to the state object, so it will be able to set a new state, but essentially it will allow the user to change state outside the state machine.

To avoid it I came to the following solutions:

I am looking into creating a very simple state machine. My state machine will contain the following 3 states:

As you know, an exit code, or sometimes known as a return code, is the code returned to a parent process by an executable. we can define our return codes something like this:

I'm trying to figure out how to deal with complex domain model using CQRS/ES approach. Let's imagine we have e.g. Order domain entity, which handles both state and behavior of order. It has a Status property with transition rules for switching between statuses (implementing State pattern or any other kind of state machine). According to DDD principles, this logic should be implemented in Order class (representing the Order model) itself, having methods like approve(), cancel(), ship(), etc.

Looking at different public examples of this kind architecture, it turns out that domain entity and aggregate root is the same, and it handles both the state and behavior and even its own projection from events. Isn't it a violation of SRP?

But my question is more concrete: if I want to process new command (and apply new event), should I reconstitute entity from event stream (i.e. from write model and write db) and call its behavioral methods (which applies events to state) to handle business rules? Or just handle commands and events themselves, without having any write-model entity?

Pseudocode to illustrate:

I'm writing a script to convert an XML feed to HTML. One part of the routine involves transforming raw State names to links with preg_replace. It's mostly working fine, but I'm having problems with "Virginia" and "West Virginia."

I recently thought of deep-diving into the various Spring projects, after seeing first-hand the tremendous utility provided to a project in my workplace. We used the Spring Statemachine project to implement a shopping cart lifecycle. This was a suggestion made by one of my colleagues while looking up code samples to implement the State Pattern in Java. Additionally, I've independently used Spring for Android to implement my first Android App.

However, on visiting the Spring homepage, I wasn't able to see the Spring Statemachine project listed there. Additionally, it wasn't mentioned in the offline documentation, either, despite there being a copy of the same.

I have two questions from this:

1. Where could one find a full listing of all the various projects provided by Spring? I tried consulting their Github page, but (for example) a filter on repos by "Kafka" returned two different repos (FYI, the project page redirects to the second URL). I was hoping for a comprehensive source like the Wikipedia page on all Apache projects
2. Why isn't the Statemachine project listed on the homepage? Is there some criteria which results in some projects being listed there, and some not?

Thank You

I have an application that runs in various states, for example state1, state2, and state3. Certain behavior of the application will depend on the state the application is in when e.g., a button is pressed, and state in turn will change based on button presses, etc.

I am wondering if there is a standard idiom or design pattern for keeping track of state changes in JavaScript. Perhaps my wording is misleading or inaccurate, so I will give an example. I might want to check state like this: