X-Git-Url: https://git.distorted.org.uk/~mdw/sod/blobdiff_plain/4307347660f48628e307f299eb4fac58ba35fd1a..bce58d373fad048a8e30bd1794953f7ebb081540:/lib/sod-structs.3

diff --git a/lib/sod-structs.3 b/lib/sod-structs.3
index 0ef69ca..35f668f 100644
--- 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;
+\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 {
@@ -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;
+\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 {
@@ -95,8 +105,8 @@ struct SodObject__ilayout {
 \h'8n'const char *name;
 \h'8n'const char *nick;
 \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;
@@ -212,7 +222,7 @@ and not really to be recommended.
 .SS The SodObject class
 The
 .B SodObject
-class defines no slots or messages.
+class defines no slots.
 Because
 .B SodObject
 has no direct superclasses,
@@ -220,8 +230,7 @@ there is only one chain,
 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
@@ -232,6 +241,79 @@ In an actual instance of
 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
@@ -253,6 +335,9 @@ A pointer to the class's nickname.
 .B size_t initsz;
 The size in bytes required to store an instance of the class.
 .TP
+.B size_t align;
+A sufficient alignment for the class's instance storage.
+.TP
 .BI "void *(*imprint)(void *" p );
 A pointer to a function:
 given a pointer
@@ -267,20 +352,6 @@ but the slots are left untouched.
 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