Community Coding : Design Patterns

lecloneur · May 12, 2021, 3:45pm

Trying out AbstractFactory pattern :

04_AbstractFactory_Example.vl (79.6 KB)

lecloneur · May 14, 2021, 10:05am

Added comments on AbstractFactory.
04_AbstractFactory.vl (137.3 KB)

And here is a first shot at FactoryMethod.
FactoryMethod.vl (38.6 KB)

Another at the ObserverPattern.
ObserverPattern.vl (44.5 KB)

Quick try at the Facad pattern with TextureFX (not sure about Dispose though)
FacadPattern.zip (9.6 KB)

tonfilm · June 24, 2022, 1:07pm

We also have the State Pattern now, see this video for the theory, and here is the implementation:

github.com/vvvv/VL-Language

[Proposal] State Machine patching pattern / library

opened 05:51PM - 20 Aug 21 UTC

antongit

proposal

# Introduction This is a patching pattern and a small library for creating an…d running State Machines' graphs directly in VL. Related to the Quest #8. For a long time I was using external Tools like [QFSM](http://qfsm.sourceforge.net/about.html) and contributions like u7angel's amazing [Automata UI](https://github.com/wirmachenbunt/AutomataUI). But I always thought - how cool will it be to make State Machines directly in VL, without the need for any external editors. We already have nodes and links, why do we need anything else? And then, I came up with a very simple solution. @gregsn has stripped it down even more and cleaned it up. This solution is made in plain VL, no magic involved. I hope one day vvvv's UI will support it a bit, reducing some copy-pasting and increasing readability. The lib was already used in two production-grade projects. # Usage scenarios The machine can be used in two different ways: 1. Basic (classic) States are just defined by their names (strings) and the rest of the system is listening to the active string. 2. Advanced States themselves can contain many different properties, operations and even complete apps, that can run **simultaneously** or only when the state is active. # How it works **States** are represented by `Processnodes`. **Transitions** between states are represented by `links` assigned to `operations`. To trigger a transition from one state to another a corresponding operation is called. An operation can be called directly (by placing a node) or by sending a string with an operation's name. # How to use it The lib will be provided as a nuget that should be referenced by your document. For now it's just a single `VL.Statemachine.vl` document and some examples. See the provided example patches. A video tutorial is coming soon. Here is the **how to** in written from. ## Basic usage 1. Reference `VL.Statemachine.vl` from your document (for now, later it will be a nuget). 2. Open ` VL.Statemachine.vl`, navigate to `Definitions > .Templates.Internal`, copy the `StateTemplate` into your document and rename it. This is one of your states. 3. Duplicate and rename this state as many times as you need. 4. Create a class for your machine and place `processnodes` of your states in it. 5. Connect them with links and assign the links to operations (which are corresponding to the transitions). 6. The `StateTemplate` pre-defines 4 inputs, enable/disable them in the `Process node` configuration in the `Patch Explorer`. If your need more inputs, just create another copy of one of the inputs and assign it to a new operation. 7. One of the states should be configured as Initial (enable the `SetAsInitialState` in its `Process node` configuration). 8. Feed the `State Manager` to your state machine. 9. Trigger transitions of the machine by placing the nodes of the corresponding operations or sending the names of operations as strings by using the `SendEvent`. **State machine class with states and transitions** ![image](https://user-images.githubusercontent.com/1189037/130272659-6e6ae5e6-c2c7-4b79-93fc-59709a0be1b2.png) **State Machine in action** ![StateMachine2](https://user-images.githubusercontent.com/1189037/130272477-45abd95a-a0b3-417b-9149-0f1322f22972.gif) **One of the states with two inputs enabled** ![image](https://user-images.githubusercontent.com/1189037/130272799-8808a630-4d12-4d18-b586-d22d501479ad.png) ## Advanced usage In order to provide properties, operations and/or whole `processnodes` to the states: 1. Define a new interface which derives from the `IState` and add Operations/Inputs/Outputs to it. 2. Use this interface in some of your states (instead of the default `IState`). 3. Use the `GetState` of the `StateManager` to get the active state and cast it to your new interface. 4. If the states are very different from each other, then their operations can by accessed by casting the active state to the particular class (without defining a new interface). **A new Interface** ![image](https://user-images.githubusercontent.com/1189037/130248729-c231ecb9-4e2f-4cb4-aba4-177fe17605bc.png) **Main state is implementing the new interface** ![image](https://user-images.githubusercontent.com/1189037/130273674-e9f3268f-8cf9-42ac-98b0-d6e974c0abdb.png) **Accessing the active state** ![image](https://user-images.githubusercontent.com/1189037/130273550-6640b012-b7fa-4ee8-8ccc-20e8a3408b5e.png) # Video presentation The pattern was presented at 13. Worldwide vvvv Meetup (starts at about 2:09): https://youtu.be/2gGPh84y-mU?t=129 # Library [VL.Statemachine.zip](https://github.com/vvvv/VL-Language/files/7023297/VL.Statemachine.zip) # Conclusion This proposal can be seen as a ready-to-use library and as general patching pattern open to any modifications / customizations. --- Also inspired by: * [State Machines in Mars Science Lab](https://www.youtube.com/watch?v=VvssxOP95s0), although they use completely different approach.