src/method-aggregate.lisp: Allow useful behaviour if no primary methods.

[sod] / doc / syntax.tex

diff --git a/doc/syntax.tex b/doc/syntax.tex
index 0e14e17..a1b650c 100644 (file)
--- a/doc/syntax.tex
+++ b/doc/syntax.tex
@@ -743,6 +743,10 @@ Properties for the @|custom| aggregating method combination:
 \item[@"before"] A code fragment containing initialization to be performed at
   the beginning of the effective method body.  The default is to insert
   nothing.
+\item[@"empty"] A code fragment executed if there are no primary methods;
+  it should usually store a suitable (identity) value in @<retvar>.  The
+  default is not to emit an effective method at all if there are no primary
+  methods.
 \item[@"first"] A code fragment to set the return value after calling the
   first applicable direct method.  The default is to use the @"each"
   fragment.