Undefining variable

2020-08-27 09:53:24 +02:00 · 2020-08-27 09:53:24 +02:00 · 73dc057cbc
parent 02ab74ac8b
commit 73dc057cbc
1 changed files with 15 additions and 0 deletions
--- a/undefining_variable.nim
+++ 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