doc/concepts.tex: Delete `no way to discover alignment for instance' claim.

Replace with a reference to the `align' class slot.

diff --git a/doc/concepts.tex b/doc/concepts.tex
index eae67aa..67dc35b 100644 (file)
--- a/doc/concepts.tex
+++ b/doc/concepts.tex
@@ -940,7 +940,8 @@ layout of an instance of some class~$C$ is described by the type @|struct
 $C$__ilayout|, and if the relevant class is known at compile time then the
 best way to discover the layout size is with the @|sizeof| operator.  Failing
 that, the size required to hold an instance of $C$ is available in a slot in
 $C$__ilayout|, and if the relevant class is known at compile time then the
 best way to discover the layout size is with the @|sizeof| operator.  Failing
 that, the size required to hold an instance of $C$ is available in a slot in

-$C$'s class object, as @|$C$__class@->cls.initsz|.
+$C$'s class object, as @|$C$__class@->cls.initsz|.  The necessary alignment,
+in bytes, is provided as @|$C$__class@->cls.align|, should this be necessary.

 
 It is not in general sufficient to declare, or otherwise allocate, an object
 of the class type $C$.  The class type only describes a single chain of the
 
 It is not in general sufficient to declare, or otherwise allocate, an object
 of the class type $C$.  The class type only describes a single chain of the


@@ -956,10 +957,6 @@ instances, so, for example, Sod doesn't make using fancy allocators which
 sometimes move objects around in memory any more difficult than it needs to
 be.
 
 sometimes move objects around in memory any more difficult than it needs to
 be.
 

-There isn't any way to discover the alignment required for a particular
-class's instances at runtime; it's best to be conservative and assume that
-the platform's strictest alignment requirement applies.
-

 The following simple function correctly allocates and returns space for an
 instance of a class given a pointer to its class object @<cls>.
 \begin{prog}
 The following simple function correctly allocates and returns space for an
 instance of a class given a pointer to its class object @<cls>.
 \begin{prog}