src/class-output.lisp (*instance-class*): Add a docstring.

[sod] / src / class-output.lisp

diff --git a/src/class-output.lisp b/src/class-output.lisp
index 1b69f6966d2ed19ef02ad524e2a9237bec367fb3..aea85d4bd3d821b470d58d4a21af772943965d67 100644 (file)
--- a/src/class-output.lisp
+++ b/src/class-output.lisp
@@ -392,7 +392,15 @@ (defmethod hook-output progn ((choff chain-offset)
 ;;; Implementation output.
 
 (export '*instance-class*)
-(defvar *instance-class*)
+(defvar *instance-class* nil
+  "The class currently being output.
+
+   This is bound during the `hook-output' traversal of a class layout for
+   `:c' output, since some of the objects traversed actually `belong' to
+   superclasses and there's no other way to find out what the reference class
+   actually is.
+
+   It may be bound at other times.")
 
 (defmethod hook-output progn ((class sod-class) (reason (eql :c)) sequencer)
   (sequence-output (stream sequencer)