From c817e0410543d00e26b346ac7588ee5ed531019d Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Thu, 13 Jul 2023 12:12:30 -0700
Subject: [PATCH 1/2] switch concept

---
 concepts/switch/.meta/config.json |  5 +++++
 concepts/switch/about.md          | 24 ++++++++++++++++++++++++
 concepts/switch/introduction.md   | 24 ++++++++++++++++++++++++
 concepts/switch/links.json        |  6 ++++++
 config.json                       |  5 +++++
 5 files changed, 64 insertions(+)
 create mode 100644 concepts/switch/.meta/config.json
 create mode 100644 concepts/switch/about.md
 create mode 100644 concepts/switch/introduction.md
 create mode 100644 concepts/switch/links.json

diff --git a/concepts/switch/.meta/config.json b/concepts/switch/.meta/config.json
new file mode 100644
index 00000000..19c01f8c
--- /dev/null
+++ b/concepts/switch/.meta/config.json
@@ -0,0 +1,5 @@
+{
+  "authors": ["colinleach"],
+  "contributors": [],
+  "blurb": "If matching on a value, especially a string, switch() can be more concise than if-else."
+}
\ No newline at end of file
diff --git a/concepts/switch/about.md b/concepts/switch/about.md
new file mode 100644
index 00000000..614e6a98
--- /dev/null
+++ b/concepts/switch/about.md
@@ -0,0 +1,24 @@
+# About
+
+The `switch()` function can be a concise replacement for a long series of `if` ... `else if` tests.
+The variable being switched on is most commonly a string, and if so the quotes can be omitted from the selector.
+
+```R
+star <- function(type) {
+  switch(type,
+    M = , # will "fall through" if no value given
+    K = "red dwarf",
+    G = "Earth-like",
+    "bigger star" # only correct for O,B,A,F
+  )
+}
+
+> star("M")
+[1] "red dwarf"
+```
+
+Note that options will only fall through if the value is left blank, as with `M` in the example above. 
+There is no need to include `break` statements as with some other languages.
+
+The final value can be a default, as here, or a `stop()` to throw an error if the conditions are intended to be exhaustive.
+Switching on an integer is slightly different: for these the default is always `NULL`.
diff --git a/concepts/switch/introduction.md b/concepts/switch/introduction.md
new file mode 100644
index 00000000..76e30975
--- /dev/null
+++ b/concepts/switch/introduction.md
@@ -0,0 +1,24 @@
+# Introduction
+
+The `switch()` function can be a concise replacement for a long series of `if` ... `else if` tests.
+The variable being switched on is most commonly a string, and if so the quotes can be omitted from the selector.
+
+```R
+star <- function(type) {
+  switch(type,
+    M = , # will "fall through" if no value given
+    K = "red dwarf",
+    G = "Earth-like",
+    "bigger star" # only correct for O,B,A,F
+  )
+}
+
+> star("M")
+[1] "red dwarf"
+```
+
+Note that options will only fall through if the value is left blank, as with `M` in the example above. 
+There is no need to include `break` statements as with some other languages.
+
+With character types, the final value can be a default, as here, or a `stop()` to throw an error if the conditions are intended to be exhaustive.
+Switching on an integer is slightly different: for these the default is always `NULL`.
diff --git a/concepts/switch/links.json b/concepts/switch/links.json
new file mode 100644
index 00000000..79cce9cb
--- /dev/null
+++ b/concepts/switch/links.json
@@ -0,0 +1,6 @@
+[
+    {
+      "url": "https://adv-r.hadley.nz/control-flow.html#switch",
+      "description": "Advanced R, 2nd ed: switch"
+    }
+  ]
\ No newline at end of file
diff --git a/config.json b/config.json
index 01ec79ac..62696f17 100644
--- a/config.json
+++ b/config.json
@@ -569,6 +569,11 @@
       "uuid": "2751b6f2-7d71-4397-b063-9bf927a57756",
       "slug": "booleans",
       "name": "Booleans"
+    },
+    {
+      "uuid": "e4c75b26-aacf-4598-a12b-88e0257bd3f5",
+      "slug": "switch",
+      "name": "Switch"
     }
   ],
   "key_features": [

From 7be6c0bbaab9aa9e0bf43664d75267bcb9ce3050 Mon Sep 17 00:00:00 2001
From: colinleach <colin.leach@comcast.net>
Date: Thu, 13 Jul 2023 12:14:54 -0700
Subject: [PATCH 2/2] minor formatting changes

---
 concepts/switch/.meta/config.json |  2 +-
 concepts/switch/links.json        | 10 +++++-----
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/concepts/switch/.meta/config.json b/concepts/switch/.meta/config.json
index 19c01f8c..5fd269af 100644
--- a/concepts/switch/.meta/config.json
+++ b/concepts/switch/.meta/config.json
@@ -2,4 +2,4 @@
   "authors": ["colinleach"],
   "contributors": [],
   "blurb": "If matching on a value, especially a string, switch() can be more concise than if-else."
-}
\ No newline at end of file
+}
diff --git a/concepts/switch/links.json b/concepts/switch/links.json
index 79cce9cb..cc123c35 100644
--- a/concepts/switch/links.json
+++ b/concepts/switch/links.json
@@ -1,6 +1,6 @@
 [
-    {
-      "url": "https://adv-r.hadley.nz/control-flow.html#switch",
-      "description": "Advanced R, 2nd ed: switch"
-    }
-  ]
\ No newline at end of file
+  {
+    "url": "https://adv-r.hadley.nz/control-flow.html#switch",
+    "description": "Advanced R, 2nd ed: switch"
+  }
+]