X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/1edb774eed8bea3f6dbde5b02db6ecd209394cf8..254bd05261479f0af6b90c6140000e23d54c691b:/doc/concepts.tex?ds=sidebyside

diff --git a/doc/concepts.tex b/doc/concepts.tex
index 8e774fe..95a0891 100644
--- a/doc/concepts.tex
+++ b/doc/concepts.tex
@@ -78,11 +78,11 @@ and a C value being returned to the sender.
 
 Every object is a \emph{direct instance} of exactly one \emph{class}.  The
 class determines which slots its instances have, which messages its instances
-can be sent, and which methods are invoked when those messages are received.
-The Sod translator's main job is to read class definitions and convert them
-into appropriate C declarations, tables, and functions.  An object cannot
-(usually) change its direct class, and the direct class of an object is not
-affected by, for example, the static type of a pointer to it.
+can be sent, and which \emph{methods} are invoked when those messages are
+received.  The Sod translator's main job is to read class definitions and
+convert them into appropriate C declarations, tables, and functions.  An
+object cannot (usually) change its direct class, and the direct class of an
+object is not affected by, for example, the static type of a pointer to it.
 
 If an object~$x$ is a direct instance of some class~$C$, then we say that $C$
 is \emph{the class of}~$x$.  Note that the class of an object is a property
@@ -537,7 +537,7 @@ Keyword arguments can be provided in three ways.
 \end{enumerate}
 
 Perhaps surprisingly, keyword arguments have a relatively small performance
-impact.  On the author's aging laptop, a call to a simple function, passing
+impact.  On the author's ageing laptop, a call to a simple function, passing
 two out of three keyword arguments, takes about 30 cycles longer than calling
 a standard function which just takes integer arguments.  On the other hand,
 quite a lot of code is involved in decoding keyword arguments, so code size
@@ -1072,7 +1072,14 @@ follows.
   initializers, \emph{and} the sender supplied a value for one or more of the
   corresponding effective initargs, then the value of the most specific such
   initarg is stored in the slot.  (For this purpose, initargs defined earlier
-  in a class definition are more specific than initargs defined later.)
+  in a class definition are more specific than initargs defined
+  later.)\footnote{%
+    This is very different from the CLOS behaviour, in which a slot is
+    initialized from the first applicable initarg in the argument list.
+    Sod's keyword-argument machinery works in two stages: firstly, the
+    arguments values are collected into a structure on entry into an
+    effective method, which loses track of the order in which the arguments
+    were passed; and only then are the direct methods invoked.}
 
 \item Otherwise, if there are any slot initializers defined which include an
   initializer expression, then the initializer expression from the most
@@ -1278,7 +1285,7 @@ functions.
 Metaobject classes are chosen in a fairly standard way.
 \begin{itemize}
 \item All metaobject definitions support a symbol-valued property, usually
-  named @|@<thing>_class| (e.g., @|slot_class|, @|method_class|), which sets
+  named @|@<thing>{}_class| (e.g., @|slot_class|, @|method_class|), which sets
   the metaobject class explicitly.  (The class for a class metaobject is
   taken from the @|lisp_class| property, because @|class_class| seems less
   meaningful.)