From f0b369cca94109a73751c671900357eccefe9e65 Mon Sep 17 00:00:00 2001
From: Michele Zaffalon <michele.zaffalon@gmail.com>
Date: Thu, 11 Jun 2020 16:24:38 +0200
Subject: [PATCH] Example of finalizer registered within constructor (#36118)

---
 base/gcutils.jl | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/base/gcutils.jl b/base/gcutils.jl
index 23ba4a82b65b5..c403e4f20f626 100644
--- a/base/gcutils.jl
+++ b/base/gcutils.jl
@@ -25,6 +25,21 @@ finalizer(my_mutable_struct) do x
     ccall(:jl_safe_printf, Cvoid, (Cstring, Cstring), "Finalizing %s.", repr(x))
 end
 ```
+
+A finalizer may be registered at object construction. In the following example note that
+we implicitly rely on the finalizer returning the newly created mutable struct `x`.
+
+# Example
+```julia
+mutable struct MyMutableStruct
+    bar
+    function MyMutableStruct(bar)
+        x = new(bar)
+        f(t) = @async println("Finalizing \$t.")
+        finalizer(f, x)
+    end
+end
+```
 """
 function finalizer(@nospecialize(f), @nospecialize(o))
     if !ismutable(o)