From 73dc057cbccc20255345031c86fd8b7a28b2e8f3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mamy=20Andr=C3=A9-Ratsimbazafy?= <mamy_github@numforge.co>
Date: Thu, 27 Aug 2020 09:53:24 +0200
Subject: [PATCH] Undefining variable

---
 undefining_variable.nim | 15 +++++++++++++++
 1 file changed, 15 insertions(+)
 create mode 100644 undefining_variable.nim

diff --git a/undefining_variable.nim b/undefining_variable.nim
new file mode 100644
index 0000000..0fffc31
--- /dev/null
+++ b/undefining_variable.nim
@@ -0,0 +1,15 @@
+# Context
+#
+# Discussion with PMunch on IRC to disallow the use of some variable
+# in a code block
+
+template undef(symbol: untyped{nkIdent}, body: untyped{nkStmtList}): untyped =
+  block:
+    template `symbol`(): untyped = {.error: "Cannot use `" & astToStr(`symbol`) & "` in this undef context".}
+    body
+
+var x = 100
+echo x
+
+undef(x):
+  echo x