From 62094ff1dc3f4284de1164b010ab129956223cf6 Mon Sep 17 00:00:00 2001
From: Jim Hester <james.f.hester@gmail.com>
Date: Mon, 24 Apr 2017 15:10:57 -0400
Subject: [PATCH 1/2] A cache function to cache arbitrary R code

---
 NAMESPACE |  1 +
 R/cache.R | 18 ++++++++++++++++++
 2 files changed, 19 insertions(+)
 create mode 100644 R/cache.R

diff --git a/NAMESPACE b/NAMESPACE
index 1736c94..1b19389 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -1,6 +1,7 @@
 # Generated by roxygen2: do not edit by hand
 
 S3method(print,memoised)
+export(cache)
 export(cache_filesystem)
 export(cache_memory)
 export(cache_s3)
diff --git a/R/cache.R b/R/cache.R
new file mode 100644
index 0000000..21052c9
--- /dev/null
+++ b/R/cache.R
@@ -0,0 +1,18 @@
+#' @export
+cache <- function(code, ..., envir = parent.frame(), cache = cache_memory()) {
+  expr <- substitute(code)
+  key <- cache$digest(c(expr, lapply(list(...), function(x) eval(x[[2L]], environment(x)))))
+  if (cache$has_key(key)) {
+    res <- cache$get(key)
+    if (res$visible) {
+      res$value
+    } else {
+      invisible(res$value)
+    }
+  } else {
+    f <- function() NULL
+    body(f) <- expr
+    environment(f) <- envir
+    (memoise(f, envir = envir, ..., cache = cache))()
+  }
+}

From 2198a679c7611348ac042c8070c2cf2b218b0338 Mon Sep 17 00:00:00 2001
From: Jim Hester <james.f.hester@gmail.com>
Date: Wed, 26 Apr 2017 13:41:29 -0400
Subject: [PATCH 2/2] Simplify call

---
 R/cache.R | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/R/cache.R b/R/cache.R
index 21052c9..f70a585 100644
--- a/R/cache.R
+++ b/R/cache.R
@@ -13,6 +13,6 @@ cache <- function(code, ..., envir = parent.frame(), cache = cache_memory()) {
     f <- function() NULL
     body(f) <- expr
     environment(f) <- envir
-    (memoise(f, envir = envir, ..., cache = cache))()
+    cache$set(key, f())
   }
 }