X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/edbd4fe2e21dea303553517790427e671de113bd..cf1b6646c06138e3103c9b561b58d9198c04c337:/doc/concepts.tex

diff --git a/doc/concepts.tex b/doc/concepts.tex
index 0533a68..945e6b9 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
@@ -169,8 +169,8 @@ in~\cite{barrett-1996:monot-super-linear-dylan}.  It works as follows.
   have no merge then they are said to be \emph{inconsistent}.
 \item The class precedence list of a class $C$ is a merge of the local
   precedence list of $C$ together with the class precedence lists of each of
-  $C$'s direct superclasses.
-\item If there are no such merges, then the definition of $C$ is invalid.
+  $C$'s direct superclasses.  If these lists are inconsistent, then the
+  definition of $C$ is invalid.
 \item Suppose that there are multiple candidate merges.  Consider the
   earliest position in these candidate merges at which they disagree.  The
   \emph{candidate classes} at this position are the classes appearing at this
@@ -1040,7 +1040,7 @@ initialization fragments.
 
 There are two kinds of initarg definitions.  \emph{User initargs} are defined
 by an explicit @|initarg| item appearing in a class definition: the item
-defines a name, type, and (optionally) a default value for the initarg.
+defines a name, a type, and (optionally) a default value for the initarg.
 \emph{Slot initargs} are defined by attaching an @|initarg| property to a
 slot or slot initializer item: the property's value determines the initarg's
 name, while the type is taken from the underlying slot type; slot initargs do
@@ -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
