doc/syntax.tex: Mention superclass list is mandatory.

[sod] / lib / sod-structs.3

diff --git a/lib/sod-structs.3 b/lib/sod-structs.3
index 5624d33..35f668f 100644 (file)
--- a/lib/sod-structs.3
+++ b/lib/sod-structs.3
@@ -69,6 +69,11 @@ struct sod_vtable {
 struct SodObject__vt_obj {
 \h'2n'const SodClass *_class;
 \h'2n'size_t _base;
 struct SodObject__vt_obj {
 \h'2n'const SodClass *_class;
 \h'2n'size_t _base;

+\h'2n'struct SodObject__vtmsgs_obj {
+\h'4n'void (*init)(SodObject *\fIme\fB, ...);
+\h'4n'void (*init__v)(SodObject *\fIme\fB, va_list);
+\h'4n'int (*teardown)(SodObject *\fIme\fB);
+\h'2n'} obj;

 };
 
 struct SodObject__ilayout {
 };
 
 struct SodObject__ilayout {


@@ -85,6 +90,11 @@ extern const struct SodClass__ilayout SodObject__classobj;
 struct SodClass__vt_obj {
 \h'2n'const SodClass *_class;
 \h'2n'size_t _base;
 struct SodClass__vt_obj {
 \h'2n'const SodClass *_class;
 \h'2n'size_t _base;

+\h'2n'struct SodClass__vtmsgs_obj {
+\h'4n'void (*init)(SodClass *\fIme\fB, ...);
+\h'4n'void (*init__v)(SodClass *\fIme\fB, va_list);
+\h'4n'int (*teardown)(SodClass *\fIme\fB);
+\h'2n'} obj;

 };
 
 struct SodObject__ilayout {
 };
 
 struct SodObject__ilayout {


@@ -97,7 +107,6 @@ struct SodObject__ilayout {
 \h'8n'size_t initsz;
 \h'8n'size_t align;
 \h'8n'void *(*imprint)(void *\fIp\fB);
 \h'8n'size_t initsz;
 \h'8n'size_t align;
 \h'8n'void *(*imprint)(void *\fIp\fB);

-\h'8n'void *(*init)(void *\fIp\fB);

 \h'8n'size_t n_supers;
 \h'8n'const SodClass *const *supers;
 \h'8n'size_t n_cpl;
 \h'8n'size_t n_supers;
 \h'8n'const SodClass *const *supers;
 \h'8n'size_t n_cpl;


@@ -213,7 +222,7 @@ and not really to be recommended.
 .SS The SodObject class
 The
 .B SodObject
 .SS The SodObject class
 The
 .B SodObject

-class defines no slots or messages.
+class defines no slots.

 Because
 .B SodObject
 has no direct superclasses,
 Because
 .B SodObject
 has no direct superclasses,


@@ -221,8 +230,7 @@ there is only one chain,
 and no inherited slots or messages,
 so the single chain contains only a vtable pointer.
 .PP
 and no inherited slots or messages,
 so the single chain contains only a vtable pointer.
 .PP

-Since there are no messages,
-and
+Since

 .B SodClass
 also has only one chain,
 the vtable contains only the standard class pointer and offset-to-base
 .B SodClass
 also has only one chain,
 the vtable contains only the standard class pointer and offset-to-base


@@ -233,6 +241,79 @@ In an actual instance of
 the class pointer contains the address of
 .B SodObject__class
 and the offset is zero.
 the class pointer contains the address of
 .B SodObject__class
 and the offset is zero.

+.PP
+The
+.B init
+message is used to initialize a newly allocated instance.
+.PP
+This message uses a custom method combination
+which works like the standard method combination
+except that default behaviour
+specific to the receiver's direct class
+is invoked if no primary or around method overrides.
+This default behaviour may be invoked multiple times
+if some method calls on its
+.B next_method
+function more than once.
+.PP
+This default behaviour is to initialize the instance's slots
+using the defined slot initializers,
+and execute the initialization fragments.
+Each slot is initialized
+using the most specific applicable initializer,
+if any.
+Slots without an initializer
+are left uninitialized.
+.PP
+Slots are initialized and initialization fragments executed together,
+a superclass at a time:
+first, the superclass's slots are initialized (if any);
+then the superclass's initialization fragments (if any) are executed,
+starting with the least specific superclass first.
+Slots and initialization fragments defined by the same class
+are processed in the order in which they appear in the class definition.
+.PP
+There are no standard keyword arguments;
+methods on subclasses are free to
+introduce their own in the usual way.
+.PP
+It is usual to provide complex initialization behaviour as
+.B after
+methods.
+This ensures that slots have been initialized as necessary
+before the method executes.
+.PP
+The
+.B teardown
+message is used to tear down an instance which is no longer required.
+.PP
+The message returns an integer flag.
+A zero value means that the instance is safe to deallocate.
+A nonzero value means that the instance should not be deallocated,
+and that it is safe for the caller to simply forget about it.
+This simple protocol may be used, for example,
+to implement a reference-counting system.
+.PP
+This message uses a custom method combination
+which works like the standard method combination
+except that default behaviour is invoked if
+no primary or around method overrides.
+This default behaviour is to execute
+each superclass's teardown fragments,
+most specific first,
+and then return zero to indicate
+that the object is ready for deallocation.
+Teardown fragments defined by the same class
+are processed in the order in which they appear
+in the class definition.
+.PP
+It is usual to provide complex teardown behaviour as
+.B before
+methods.
+Logic to decide whether to allow deallocation
+is usually implemented as
+.B around
+methods.

 .
 .SS The SodClass class
 The
 .
 .SS The SodClass class
 The


@@ -271,20 +352,6 @@ but the slots are left untouched.
 The function returns its argument
 .IR p .
 .TP
 The function returns its argument
 .IR p .
 .TP

-.BI "void *(*init)(void *" p );
-A pointer to a function:
-given a pointer
-.I p
-to at least
-.I initsz
-bytes of appropriately aligned memory,
-initialize an instance of the class in it:
-all of the vtable and class pointers are initialized,
-as are slots for which initializers are defined.
-Other slots are left untouched.
-The function returns its argument
-.IR p .
-.TP

 .B size_t n_supers;
 The number of direct superclasses.
 (This is zero exactly in the case of
 .B size_t n_supers;
 The number of direct superclasses.
 (This is zero exactly in the case of


@@ -897,6 +964,27 @@ defined as
 .IB an , 
 .B ...);
 .PP
 .IB an , 
 .B ...);
 .PP

+or a standard message which takes keyword arguments,
+defined as
+.IP
+.I tr
+.IB m ( \c
+.I t1
+.IB a1 ,
+.RB ... ,
+.I tn
+.IB an ?\&
+.IR tn +1
+.IR kn +1
+.RB [ =
+.IR dn +1] \c
+.B ,
+.I tm
+.I km
+.RB [ =
+.IR dm ] \c
+);
+.PP

 two entry points are defined:
 the usual `main' entry point
 which accepts a variable number of
 two entry points are defined:
 the usual `main' entry point
 which accepts a variable number of


@@ -904,7 +992,8 @@ arguments,
 and a `valist' entry point
 which accepts an argument of type
 .B va_list
 and a `valist' entry point
 which accepts an argument of type
 .B va_list

-in place of the variable portion of the argument list.
+in place of the variable portion of the argument list
+or keywords.

 .IP
 .I tr
 .BI (* m )( \c
 .IP
 .I tr
 .BI (* m )( \c


@@ -954,6 +1043,7 @@ somewhat less ugly.
 If
 .I m
 takes a variable number of arguments,
 If
 .I m
 takes a variable number of arguments,

+or keyword arguments,

 the macro is more complicated
 and is only available in compilers advertising C99 support,
 but the effect is the same.
 the macro is more complicated
 and is only available in compilers advertising C99 support,
 but the effect is the same.