X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/3dca7758421664a838c54b273bd9221f02072045..65aaa02c8b8a0226b13724934e12f4bd871cdc19:/lib/sod-structs.3

diff --git a/lib/sod-structs.3 b/lib/sod-structs.3
index 6aefc9d..a6c9db2 100644
--- a/lib/sod-structs.3
+++ b/lib/sod-structs.3
@@ -7,23 +7,26 @@
 .
 .\"----- Licensing notice ---------------------------------------------------
 .\"
-.\" This file is part of the Sensble Object Design, an object system for C.
+.\" This file is part of the Sensible Object Design, an object system for C.
 .\"
 .\" SOD is free software; you can redistribute it and/or modify
-.\" it under the terms of the GNU General Public License as published by
-.\" the Free Software Foundation; either version 2 of the License, or
-.\" (at your option) any later version.
+.\" it under the terms of the GNU Library General Public License as
+.\" published by the Free Software Foundation; either version 2 of the
+.\" License, or (at your option) any later version.
 .\"
 .\" SOD is distributed in the hope that it will be useful,
 .\" but WITHOUT ANY WARRANTY; without even the implied warranty of
 .\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-.\" GNU General Public License for more details.
+.\" GNU Library General Public License for more details.
 .\"
-.\" You should have received a copy of the GNU General Public License
-.\" along with SOD; if not, write to the Free Software Foundation,
-.\" Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+.\" You should have received a copy of the GNU Library General Public
+.\" License along with SOD; if not, write to the Free
+.\" Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
+.\" MA 02111-1307, USA.
 .
+.\" Highlight using terminal escapes, rather than overstriking.
 .\"\X'tty: sgr 1'
+.
 .\" String definitions and font selection.
 .ie t \{\
 .  ds o \(bu
@@ -192,11 +195,13 @@ has no direct superclasses,
 and
 .B SodClass
 is its own metaclass.
-It is not possible to define root classes because of circularities:
+It is not possible to define root classes in module files
+because of circularities:
 .B SodObject
 has
 .B SodClass
-as its metaclass, and
+as its metaclass,
+and
 .B SodClass
 is a subclass of
 .BR SodObject .
@@ -546,7 +551,8 @@ and this is followed by corresponding members
 .IB a ;
 .PP
 for each of
-.IR C 's superclasses
+.IR C 's
+superclasses
 .IR A
 in the same chain in some (unimportant) order.
 A `pointer to
@@ -617,13 +623,17 @@ each
 .B ichain
 must have as a prefix the
 .B ichain
-for each superclass in the same chain, and
-each slot must be stored in exactly one place.
+for each superclass in the same chain,
+and each slot must be stored in exactly one place.
 The layout of vtables doesn't have this second requirement:
 it doesn't matter that there are
 multiple method entry pointers
 for the same effective method
 as long as they all work correctly.
+Indeed, it's essential that they do,
+because each chain's method entry function
+will need to apply a different offset to the receiver pointer
+before invoking the effective method.
 .PP
 A vtable for a class
 .I C
@@ -655,10 +665,8 @@ extern const union \fIC\fB__vtu_\fIh\fB \fIC\fB__vtable_\fIh\fB;
 .fi
 .PP
 The outer layer is a
-.IP
 .B union
 .IB C __vtu_ h
-.PP
 containing a member
 .IP
 .B struct
@@ -718,7 +726,7 @@ of
 The metaclass
 .I R
 of
-.IR O .
+.I O
 is then the
 .I root metaclass
 of
@@ -781,7 +789,7 @@ be the most specific superclass of
 in the same chain as
 .IR J .
 Then, if there is currently no class pointer of type
-.I Q
+.IR Q ,
 then add a member
 .RS
 .IP
@@ -825,7 +833,7 @@ If class
 .I A
 defines any messages,
 and there is currently no member
-.I a
+.IR a ,
 then add a member
 .RS
 .IP