## Intentions

• R6P is an amalgamation of useful design patterns in R
• R6P explains how a design pattern works and when to use a design pattern
• R6P provides examples that show how to implement each design pattern in R

Caution: Most functions and classes provided by the R6P package are not useful by themselves. This is because design patterns are employed in a specific context. R6P implementations are designed for demonstration purposes. Instead of directly using the design pattern as they appear in the package, you’d have to adjust the source code (provided in the examples) to the problem you are trying to solve.

## Introduction

Build robust and maintainable software with object-oriented design patterns in R. Design patterns abstract and present in neat, well-defined components and interfaces the experience of many software designers and architects over many years of solving similar problems. These are solutions that have withstood the test of time with respect to re-usability, flexibility, and maintainability. ‘R6P’ provides abstract base classes with examples for a few known design patterns. The patterns were selected by their applicability to analytic projects in R. Using these patterns in R projects have proven effective in dealing with the complexity that data-driven applications possess.

This package is based on the work of Gamma1995, and Fowler2002.

### Should I use design patterns?

Design patterns represent an alternative to design: rather than designing a new mechanism from scratch, just apply a well-known design pattern. For the most part, this is good: design patterns arose because they solve common problems, and because they are generally agreed to provide clean solutions. If a design pattern works well in a particular situation, it will probably be hard for you to come up with a different approach that is better.

The greatest risk with design patterns is over-application. Not every problem can be solved cleanly with an existing design pattern; don’t try to force a problem into a design pattern when a custom approach will be cleaner. Using design patterns doesn’t automatically improve a software system; it only does so if the design patterns fit. As with many ideas in software design, the notion that design patterns are good doesn’t necessarily mean that more design patterns are better.

## Installation

You can install the released version of R6P from CRAN with:

install.packages("R6P")

And the development version from GitHub with:

# install.packages("devtools")
devtools::install_github("tidylab/R6P")

## References

Fowler, Martin. 2002. Patterns of enterprise application architecture. Addison-Wesley Longman Publishing Co., Inc.

Gamma, Erich, Richard Helm, Ralph Johnson, and John Vlissides. 1995. Design patterns: elements of reusable object-oriented software. Pearson Education India.

Ousterhout, John. 2018. A Philosophy of Software Design. Yaknyam Press.