---
title: "Sharing caches across projects"
author: "Nathan Sheffield"
date: "`r Sys.Date()`"
vignette: >
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteIndexEntry{Sharing caches across projects}
output: knitr:::html_vignette
---

# Sharing caches across projects

By default, `simpleCache` will store its caches for your project in the `RCACHE.DIR` global option. This is designed to be a project-specific directory, so I have a different RCache dir for each of my projects. Sometimes, though, I want to share caches across projects, and so it's useful to have a definition of a shared cache directory. I think of this as a general resource. For instance, I use this to store the location of all CpGs in the human genome, which I use repeatedly in many projects.

To solve this problem, `simpleCache` uses a second global option, `SHARE.RCACHE.DIR`, which you can access with the convenience setter `setSharedCacheDir()`. Then, you use `simpleCache` as normal but with the additional parameter of cacheDir, or the convenience alias `simpleCacheShared()`, as outlined below:

```{r Try it out}
library(simpleCache)
cacheDir = tempdir()
setSharedCacheDir(cacheDir)
simpleCacheShared("normSample", { rnorm(1e7, 0,1) }, recreate=TRUE)
simpleCacheShared("normSample", { rnorm(1e7, 0,1) })
```

```{r Clean up}
deleteCaches("normSample", force=TRUE)
```