\chapter{Concepts} \label{ch:concepts}
%%%--------------------------------------------------------------------------
-\section{Operational model} \label{sec:concepts.model}
-
-The Sod translator runs as a preprocessor, similar in nature to the
-traditional Unix \man{lex}{1} and \man{yacc}{1} tools. The translator reads
-a \emph{module} file containing class definitions and other information, and
-writes C~source and header files. The source files contain function
-definitions and static tables which are fed directly to a C~compiler; the
-header files contain declarations for functions and data structures, and are
-included by source files -- whether hand-written or generated by Sod -- which
-makes use of the classes defined in the module.
-
-Sod is not like \Cplusplus: it makes no attempt to `enhance' the C language
-itself. Sod module files describe classes, messages, methods, slots, and
-other kinds of object-system things, and some of these descriptions need to
-contain C code fragments, but this code is entirely uninterpreted by the Sod
-translator.\footnote{%
- As long as a code fragment broadly follows C's lexical rules, and properly
- matches parentheses, brackets, and braces, the Sod translator will copy it
- into its output unchanged. It might, in fact, be some other kind of C-like
- language, such as Objective~C or \Cplusplus. Or maybe even
- Objective~\Cplusplus, because if having an object system is good, then
- having three must be really awesome.} %
-
-The Sod translator is not a closed system. It is written in Common Lisp, and
-can load extension modules which add new input syntax, output formats, or
-altered behaviour. The interface for writing such extensions is described in
-\xref{p:lisp}. Extensions can change almost all details of the Sod object
-system, so the material in this manual must be read with this in mind: this
-manual describes the base system as provided in the distribution.
-
-%%%--------------------------------------------------------------------------
\section{Modules} \label{sec:concepts.modules}
A \emph{module} is the top-level syntactic unit of input to the Sod
If an object is a direct instance of class~$C$ then the object is also an
(indirect) instance of every superclass of $C$.
-If $C$ has a proper superclass $B$, then $B$ is not allowed to have $C$ has a
-direct superclass. In different terms, if we construct a graph, whose
-vertices are classes, and draw an edge from each class to each of its direct
-superclasses, then this graph must be acyclic. In yet other terms, the `is a
-superclass of' relation is a partial order on classes.
+If $C$ has a proper superclass $B$, then $B$ must not have $C$ as a direct
+superclass. In different terms, if we construct a graph, whose vertices are
+classes, and draw an edge from each class to each of its direct superclasses,
+then this graph must be acyclic. In yet other terms, the `is a superclass
+of' relation is a partial order on classes.
\subsubsection{The class precedence list}
This partial order is not quite sufficient for our purposes. For each class
list, i.e., $B$ is a more specific superclass of $C$ than $A$ is.
\end{itemize}
The default linearization algorithm used in Sod is the \emph{C3} algorithm,
-which has a number of good properties described in~\cite{FIXME:C3}.
+which has a number of good properties described in~\cite{Barrett:1996:MSL}.
It works as follows.
\begin{itemize}
\item A \emph{merge} of some number of input lists is a single list
not be a direct superclass of $C$.
Superclass links must obey the following rule: if $C$ is a class, then there
-must be no three superclasses $X$, $Y$ and~$Z$ of $C$ such that $Z$ is the
-link superclass of both $X$ and $Y$. As a consequence of this rule, the
-superclasses of $C$ can be partitioned into linear \emph{chains}, such that
-superclasses $A$ and $B$ are in the same chain if and only if one can trace a
-path from $A$ to $B$ by following superclass links, or \emph{vice versa}.
+must be no three distinct superclasses $X$, $Y$ and~$Z$ of $C$ such that $Z$
+is the link superclass of both $X$ and $Y$. As a consequence of this rule,
+the superclasses of $C$ can be partitioned into linear \emph{chains}, such
+that superclasses $A$ and $B$ are in the same chain if and only if one can
+trace a path from $A$ to $B$ by following superclass links, or \emph{vice
+versa}.
Since a class links only to one of its proper superclasses, the classes in a
chain are naturally ordered from most- to least-specific. The least specific
\subsubsection{Slot initializers}
As well as defining slot names and types, a class can also associate an
\emph{initial value} with each slot defined by itself or one of its
-subclasses. A class $C$ provides an \emph{initialization function} (see
+subclasses. A class $C$ provides an \emph{initialization message} (see
\xref{sec:concepts.lifecycle.birth}, and \xref{sec:structures.root.sodclass})
-which sets the slots of a \emph{direct} instance of the class to the correct
-initial values. If several of $C$'s superclasses define initializers for the
-same slot then the initializer from the most specific such class is used. If
-none of $C$'s superclasses define an initializer for some slot then that slot
-will be left uninitialized.
+whose methods set the slots of a \emph{direct} instance of the class to the
+correct initial values. If several of $C$'s superclasses define initializers
+for the same slot then the initializer from the most specific such class is
+used. If none of $C$'s superclasses define an initializer for some slot then
+that slot will be left uninitialized.
The initializer for a slot with scalar type may be any C expression. The
initializer for a slot with aggregate type must contain only constant
stash them in a dynamically allocated private structure, and leave a pointer
to it in a slot. (This will also help preserve binary compatibility, because
the private structure can grow more members as needed. See
-\xref{sec:fixme.compatibility} for more details.
+\xref{sec:fixme.compatibility} for more details.)
+
+
+\subsubsection{Vtables}
+
\subsubsection{Class objects}
In Sod's object system, classes are objects too. Therefore classes are
A class object's slots contain or point to useful information, tables and
functions for working with that class's instances. (The @|SodClass| class
-doesn't define any messages, so it doesn't have any methods. In Sod, a class
-slot containing a function pointer is not at all the same thing as a method.)
+doesn't define any messages, so it doesn't have any methods other than for
+the @|SodObject| lifecycle messages @|init| and @|teardown|; see
+\xref{sec:concepts.lifecycle}. In Sod, a class slot containing a function
+pointer is not at all the same thing as a method.)
\subsubsection{Conversions}
-Suppose one has a value of type pointer to class type of some class~$C$, and
-wants to convert it to a pointer to class type of some other class~$B$.
+Suppose one has a value of type pointer-to-class-type for some class~$C$, and
+wants to convert it to a pointer-to-class-type for some other class~$B$.
There are three main cases to distinguish.
\begin{itemize}
\item If $B$ is a superclass of~$C$, in the same chain, then the conversion
pointer. The conversion can be performed using the appropriate generated
upcast macro (see below); the general case is handled by the macro
\descref{SOD_XCHAIN}{mac}.
-\item If $B$ is a subclass of~$C$ then the conversion is an \emph{upcast};
+\item If $B$ is a subclass of~$C$ then the conversion is a \emph{downcast};
otherwise the conversion is a~\emph{cross-cast}. In either case, the
conversion can fail: the object in question might not be an instance of~$B$
- at all. The macro \descref{SOD_CONVERT}{mac} and the function
+ after all. The macro \descref{SOD_CONVERT}{mac} and the function
\descref{sod_convert}{fun} perform general conversions. They return a null
- pointer if the conversion fails. (There are therefore your analogue to the
- \Cplusplus @|dynamic_cast<>| operator.)
+ pointer if the conversion fails. (These are therefore your analogue to the
+ \Cplusplus\ @|dynamic_cast<>| operator.)
\end{itemize}
The Sod translator generates macros for performing both in-chain and
cross-chain upcasts. For each class~$C$, and each proper superclass~$B$
Keyword arguments are provided as a general feature for C functions.
However, Sod has special support for messages which accept keyword arguments
-(\xref{sec:concepts.methods.keywords}); and they play an essential role in
+(\xref{sec:concepts.methods.keywords}); and they play an essential rôle in
the instance construction protocol (\xref{sec:concepts.lifecycle.birth}).
%%%--------------------------------------------------------------------------
it or any of its superclasses.
Like messages, direct methods define argument lists and return types, but
-they may also have a \emph{body}, and a \emph{role}.
+they may also have a \emph{body}, and a \emph{rôle}.
A direct method need not have the same argument list or return type as its
message. The acceptable argument lists and return types for a method depend
on the message, in particular its method combination
-(\xref{sec:concepts.methods.combination}), and the method's role.
+(\xref{sec:concepts.methods.combination}), and the method's rôle.
A direct method body is a block of C code, and the Sod translator usually
defines, for each direct method, a function with external linkage, whose body
together to form the \emph{effective method} for that particular class and
message. Direct methods can be combined into an effective method in
different ways, according to the \emph{method combination} specified by the
-message. The method combination determines which direct method roles are
-acceptable, and, for each role, the appropriate argument lists and return
+message. The method combination determines which direct method rôles are
+acceptable, and, for each rôle, the appropriate argument lists and return
types.
One direct method, $M$, is said to be more (resp.\ less) \emph{specific} than
\subsubsection{The standard method combination}
The default method combination is called the \emph{standard method
combination}; other method combinations are useful occasionally for special
-effects. The standard method combination accepts four direct method roles,
+effects. The standard method combination accepts four direct method rôles,
called `primary' (the default), @|before|, @|after|, and @|around|.
All direct methods subject to the standard method combination must have
constructed: the vtables contain null pointers in place of pointers to method
entry functions.
+\begin{figure}
+ \hbox to\hsize{\hss\hbox{\begin{tikzpicture}
+ [order/.append style={color=green!70!black},
+ code/.append style={font=\sffamily},
+ action/.append style={font=\itshape},
+ method/.append style={rectangle, draw=black, thin, fill=blue!30,
+ text height=\ht\strutbox, text depth=\dp\strutbox,
+ minimum width=40mm}]
+
+ \def\delgstack#1#2#3{
+ \node (#10) [method, #2] {#3};
+ \node (#11) [method, above=6mm of #10] {#3};
+ \draw [->] ($(#10.north)!.5!(#10.north west) + (0mm, 1mm)$) --
+ ++(0mm, 4mm)
+ node [code, left=4pt, midway] {next_method};
+ \draw [<-] ($(#10.north)!.5!(#10.north east) + (0mm, 1mm)$) --
+ ++(0mm, 4mm)
+ node [action, right=4pt, midway] {return};
+ \draw [->] ($(#11.north)!.5!(#11.north west) + (0mm, 1mm)$) --
+ ++(0mm, 4mm)
+ node [code, left=4pt, midway] {next_method}
+ node (ld) [above] {$\smash\vdots\mathstrut$};
+ \draw [<-] ($(#11.north)!.5!(#11.north east) + (0mm, 1mm)$) --
+ ++(0mm, 4mm)
+ node [action, right=4pt, midway] {return}
+ node (rd) [above] {$\smash\vdots\mathstrut$};
+ \draw [->] ($(ld.north) + (0mm, 1mm)$) -- ++(0mm, 4mm)
+ node [code, left=4pt, midway] {next_method};
+ \draw [<-] ($(rd.north) + (0mm, 1mm)$) -- ++(0mm, 4mm)
+ node [action, right=4pt, midway] {return};
+ \node (p) at ($(ld.north)!.5!(rd.north)$) {};
+ \node (#1n) [method, above=5mm of p] {#3};
+ \draw [->, order] ($(#10.south east) + (4mm, 1mm)$) --
+ ($(#1n.north east) + (4mm, -1mm)$)
+ node [midway, right, align=left]
+ {Most to \\ least \\ specific};}
+
+ \delgstack{a}{}{@|around| method}
+ \draw [<-] ($(a0.south)!.5!(a0.south west) - (0mm, 1mm)$) --
+ ++(0mm, -4mm);
+ \draw [->] ($(a0.south)!.5!(a0.south east) - (0mm, 1mm)$) --
+ ++(0mm, -4mm)
+ node [action, right=4pt, midway] {return};
+
+ \draw [->] ($(an.north)!.6!(an.north west) + (0mm, 1mm)$) --
+ ++(-8mm, 8mm)
+ node [code, midway, left=3mm] {next_method}
+ node (b0) [method, above left = 1mm + 4mm and -6mm - 4mm] {};
+ \node (b1) [method] at ($(b0) - (2mm, 2mm)$) {};
+ \node (bn) [method] at ($(b1) - (2mm, 2mm)$) {@|before| method};
+ \draw [->, order] ($(bn.west) - (6mm, 0mm)$) -- ++(12mm, 12mm)
+ node [midway, above left, align=center] {Most to \\ least \\ specific};
+ \draw [->] ($(b0.north east) + (-10mm, 1mm)$) -- ++(8mm, 8mm)
+ node (p) {};
+
+ \delgstack{m}{above right=1mm and 0mm of an.west |- p}{Primary method}
+ \draw [->] ($(mn.north)!.5!(mn.north west) + (0mm, 1mm)$) -- ++(0mm, 4mm)
+ node [code, left=4pt, midway] {next_method}
+ node [above right = 0mm and -8mm]
+ {$\vcenter{\hbox{\Huge\textcolor{red}{!}}}
+ \vcenter{\hbox{\begin{tabular}[c]{l}
+ \textsf{next_method} \\
+ pointer is null
+ \end{tabular}}}$};
+
+ \draw [->, color=blue, dotted]
+ ($(m0.south)!.2!(m0.south east) - (0mm, 1mm)$) --
+ ($(an.north)!.2!(an.north east) + (0mm, 1mm)$)
+ node [midway, sloped, below] {Return value};
+
+ \draw [<-] ($(an.north)!.6!(an.north east) + (0mm, 1mm)$) --
+ ++(8mm, 8mm)
+ node [action, midway, right=3mm] {return}
+ node (f0) [method, above right = 1mm and -6mm] {};
+ \node (f1) [method] at ($(f0) + (-2mm, 2mm)$) {};
+ \node (fn) [method] at ($(f1) + (-2mm, 2mm)$) {@|after| method};
+ \draw [<-, order] ($(f0.east) + (6mm, 0mm)$) -- ++(-12mm, 12mm)
+ node [midway, above right, align=center]
+ {Least to \\ most \\ specific};
+ \draw [<-] ($(fn.north west) + (6mm, 1mm)$) -- ++(-8mm, 8mm);
+
+ \end{tikzpicture}}\hss}
+
+ \caption{The standard method combination}
+ \label{fig:concepts.methods.stdmeth}
+\end{figure}
+
The effective method for a message with standard method combination works as
-follows.
+follows (see also~\xref{fig:concepts.methods.stdmeth}).
\begin{enumerate}
-\item If any applicable methods have the @|around| role, then the most
+\item If any applicable methods have the @|around| rôle, then the most
specific such method, with respect to the class of the receiving object, is
invoked.
If there any remaining @|around| methods, then @|next_method| invokes the
next most specific such method, returning whichever value that method
- returns; otherwise the behaviour of @|next_method| is to invoke the before
- methods (if any), followed by the most specific primary method, followed by
- the @|around| methods (if any), and to return whichever value was returned
- by the most specific primary method, as described in the following items.
- That is, the behaviour of the least specific @|around| method's
- @|next_method| function is exactly the behaviour that the effective method
- would have if there were no @|around| methods. Note that if the
- least-specific @|around| method calls its @|next_method| more than once
- then the whole sequence of @|before|, primary, and @|after| methods occurs
- multiple times.
+ returns; otherwise the behaviour of @|next_method| is to invoke the
+ @|before| methods (if any), followed by the most specific primary method,
+ followed by the @|after| methods (if any), and to return whichever value
+ was returned by the most specific primary method, as described in the
+ following items. That is, the behaviour of the least specific @|around|
+ method's @|next_method| function is exactly the behaviour that the
+ effective method would have if there were no @|around| methods. Note that
+ if the least-specific @|around| method calls its @|next_method| more than
+ once then the whole sequence of @|before|, primary, and @|after| methods
+ occurs multiple times.
The value returned by the most specific @|around| method is the value
returned by the effective method.
-\item If any applicable methods have the @|before| role, then they are all
+\item If any applicable methods have the @|before| rôle, then they are all
invoked, starting with the most specific.
\item The most specific applicable primary method is invoked.
returned to the least specific @|around| method, which called it via its
own @|next_method| function.
-\item If any applicable methods have the @|after| role, then they are all
+\item If any applicable methods have the @|after| rôle, then they are all
invoked, starting with the \emph{least} specific. (Hence, the most
specific @|after| method is invoked with the most `afterness'.)
A typical use for @|around| methods is to allow a base class to set up the
dynamic environment appropriately for the primary methods of its subclasses,
-e.g., by claiming a lock, and restore it afterwards.
+e.g., by claiming a lock, and releasing it afterwards.
The @|next_method| function provided to methods with the primary and
-@|around| roles accepts the same arguments, and returns the same type, as the
+@|around| rôles accepts the same arguments, and returns the same type, as the
message, except that one or two additional arguments are inserted at the
front of the argument list. The first additional argument is always the
receiving object, @|me|. If the message accepts a variable argument suffix,
of the argument pointer (so the method body can process the variable argument
suffix itself, and still pass a fresh copy on to the next method).
-A method with the primary or @|around| role may use the convenience macro
+A method with the primary or @|around| rôle may use the convenience macro
@|CALL_NEXT_METHOD|, which takes no arguments itself, and simply calls
@|next_method| with appropriate arguments: the receiver @|me| pointer, the
argument pointer @|sod__master_ap| (if applicable), and the method's
the applicable primary methods in turn and aggregate the return values from
each.
-The aggregating method combinations accept the same four roles as the
+The aggregating method combinations accept the same four rôles as the
standard method combination, and @|around|, @|before|, and @|after| methods
work in the same way.
in \xref{sec:fixme.custom-aggregating-method-combination}.
+\subsection{Sending messages in C} \label{sec:concepts.methods.c}
+
+Each instance is associated with its direct class [FIXME]
+
+The effective methods for each class are determined at translation time, by
+the Sod translator. For each effective method, one or more \emph{method
+entry functions} are constructed. A method entry function has three
+responsibilities.
+\begin{itemize}
+\item It converts the receiver pointer to the correct type. Method entry
+ functions can perform these conversions extremely efficiently: there are
+ separate method entries for each chain of each class which can receive a
+ message, so method entry functions are in the privileged situation of
+ knowing the \emph{exact} class of the receiving object.
+\item If the message accepts a variable-length argument tail, then two method
+ entry functions are created for each chain of each class: one receives a
+ variable-length argument tail, as intended, and captures it in a @|va_list|
+ object; the other accepts an argument of type @|va_list| in place of the
+ variable-length tail and arranges for it to be passed along to the direct
+ methods.
+\item It invokes the effective method with the appropriate arguments. There
+ might or might not be an actual function corresponding to the effective
+ method itself: the translator may instead open-code the effective method's
+ behaviour into each method entry function; and the machinery for handling
+ `delegation chains', such as is used for @|around| methods and primary
+ methods in the standard method combination, is necessarily scattered among
+ a number of small functions.
+\end{itemize}
+
+
\subsection{Messages with keyword arguments}
\label{sec:concepts.methods.keywords}
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}
- void *allocate_instance(const SodClass *cls) \\ \ind
+ void *allocate_instance(const SodClass *cls) \\ \ind
\{ return malloc(cls@->cls.initsz); \}
\end{prog}
Once an instance's storage has been imprinted, it is technically possible to
send messages to the instance; however the instance's slots are still
-uninitialized at this point, the applicable methods are unlikely to do much
-of any use unless they've been written specifically for the purpose.
+uninitialized at this point, so the applicable methods are unlikely to do
+much of any use unless they've been written specifically for the purpose.
The following simple function imprints storage at address @<p> as an instance
of a class, given a pointer to its class object @<cls>.
\begin{prog}
- void imprint_instance(const SodClass *cls, void *p) \\ \ind
+ void imprint_instance(const SodClass *cls, void *p) \\ \ind
\{ cls@->cls.imprint(p); \}
\end{prog}
Details of initialization are necessarily class-specific, but typically it
involves setting the instance's slots to appropriate values, and possibly
-linking it into some larger data structure to keep track of it.
+linking it into some larger data structure to keep track of it. It is
+possible for initialization methods to attempt to allocate resources, but
+this must be done carefully: there is currently no way to report an error
+from object initialization, so the object must be marked as incompletely
+initialized, and left in a state where it will be safe to tear down later.
Initialization is performed by sending the imprinted instance an @|init|
message, defined by the @|SodObject| class. This message uses a nonstandard
Slots are initialized in a well-defined order.
\begin{itemize}
-\item Slots defined by a more specific superclasses are initialized after
- slots defined by a less specific superclass.
+\item Slots defined by a more specific superclass are initialized after slots
+ defined by a less specific superclass.
\item Slots defined by the same class are initialized in the order in which
their definitions appear.
\end{itemize}
fragments are executed with @|me| bound to an instance pointer of the
appropriate superclass type, immediately after that superclass's slots (if
any) have been initialized; therefore, fragments defined by a more specific
-superclass are executed after fragments defined by a more specific
+superclass are executed after fragments defined by a less specific
superclass. A class may define more than one initialization fragment: the
fragments are executed in the order in which they appear in the class
definition. It is possible for an initialization fragment to use @|return|
by an explicit @|initarg| item appearing in a class definition: the item
defines a name, 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 determines the initarg's name,
-while the type is taken from the underlying slot type; slot initargs do not
-have default values. Both kinds define a \emph{direct initarg} for the
+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
+not have default values. Both kinds define a \emph{direct initarg} for the
containing class.
Initargs are inherited. The \emph{applicable} direct initargs for an @|init|
\descref{sod_destroy}[function]{fun}.
\subsubsection{Teardown}
-Details of initialization are necessarily class-specific, but typically it
-involves setting the instance's slots to appropriate values, and possibly
-linking it into some larger data structure to keep track of it.
+Details of teardown are necessarily class-specific, but typically it
+involves releasing resources held by the instance, and disentangling it from
+any data structures it might be linked into.
Teardown is performed by sending the instance the @|teardown| message,
defined by the @|SodObject| class. The message returns an integer, used as a
This simple protocol can be used, for example, to implement a reference
counting system, as follows.
\begin{prog}
- [nick = ref] \\
- class ReferenceCountedObject \{ \\ \ind
- unsigned nref = 1; \\-
- void inc() \{ me@->ref.nref++; \} \\-
- [role = around] \\
- int obj.teardown() \\
- \{ \\ \ind
- if (--\,--me@->ref.nref) return (1); \\
- else return (CALL_NEXT_METHOD); \- \\
- \} \- \\
+ [nick = ref] \\
+ class ReferenceCountedObject: SodObject \{ \\ \ind
+ unsigned nref = 1; \\-
+ void inc() \{ me@->ref.nref++; \} \\-
+ [role = around] \\
+ int obj.teardown() \\
+ \{ \\ \ind
+ if (--\,--me@->ref.nref) return (1); \\
+ else return (CALL_NEXT_METHOD); \-\\
+ \} \-\\
\}
\end{prog}
-This message uses a nonstandard method combination which works like the
-standard combination, except that the \emph{default behaviour}, if there is
-no overriding method, is to execute the superclass's teardown fragments, and
-to return zero. This default behaviour may be invoked multiple times if some
-method calls on its @|next_method| more than once, unless some other method
-takes steps to prevent this.
+The @|teardown| message uses a nonstandard method combination which works
+like the standard combination, except that the \emph{default behaviour}, if
+there is no overriding method, is to execute the superclass's teardown
+fragments, and to return zero. This default behaviour may be invoked
+multiple times if some method calls on its @|next_method| more than once,
+unless some other method takes steps to prevent this.
A class can define \emph{teardown fragments}: pieces of literal code to be
executed to shut down an instance. Each superclass's teardown fragments are
executed with @|me| bound to an instance pointer of the appropriate
superclass type; fragments defined by a more specific superclass are executed
-before fragments defined by a more specific superclass. A class may define
+before fragments defined by a less specific superclass. A class may define
more than one teardown fragment: the fragments are executed in the order in
which they appear in the class definition. It is possible for an
initialization fragment to use @|return| or @|goto| for special control-flow
%%%--------------------------------------------------------------------------
\section{Metaclasses} \label{sec:concepts.metaclasses}
+%%%--------------------------------------------------------------------------
+\section{Compatibility considerations} \label{sec:concepts.compatibility}
+
+Sod doesn't make source-level compatibility especially difficult. As long as
+classes, slots, and messages don't change names or dissappear, and slots and
+messages retain their approximate types, everything will be fine.
+
+Binary compatibility is much more difficult. Unfortunately, Sod classes have
+rather fragile binary interfaces.\footnote{%
+ Research suggestion: investigate alternative instance and vtable layouts
+ which improve binary compatibility, probably at the expense of instance
+ compactness, and efficiency of slot access and message sending. There may
+ be interesting trade-offs to be made.} %
+
+If instances are allocated [FIXME]
+
%%%----- That's all, folks --------------------------------------------------
%%% Local variables: