Merge pull request #129 from Glasses-Neo/feature/id_128

Feature/id 128

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/)
 and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
+### Added
+- `isInstanceOf` to check whether a variable can be converted to a certain protocol
 
 ## [v0.7.1] -2023-10-21
 ### Fixed

src/oolib.nim

@@ -161,3 +161,15 @@ macro protocoled*(typeDef: untyped): untyped =
   result = typeDef
 
   ProtocolTable[protocolName.basename.strVal] = typeDef[2]
+
+macro isInstanceOf*(v, T: untyped): untyped =
+  return block:
+    if ProtocolTable.hasKey(T.strVal):
+      quote do:
+        when compiles(`v`.toProtocol()):
+          `v`.toProtocol().type is `T`
+        else:
+          false
+    else:
+      quote do:
+        `v`.type is `T`

tests/is_instanceof.nim

@@ -0,0 +1,28 @@
+discard """
+  action: "compile"
+"""
+
+import
+  std/unittest,
+  ../src/oolib
+
+protocol Readable:
+  var text: string
+
+class Book impl Readable:
+  var title: string
+  var text: string = ""
+
+class Human:
+  var name: string
+
+let
+  book = Book.new(title = "Autobiography")
+  me = Human.new("Me")
+
+check book.isInstanceOf(Readable)
+check book.isInstanceOf(Book)
+check me.isInstanceOf(Human)
+
+check not me.isInstanceOf(Readable)
+check not book.isInstanceOf(Human)