Working with SPRAAK classes and objects

The syntax

Some examples

For a more elaborate example see taipan_cpp.c (C++ style multiple inheritance) and taipan_objc.c (single inheritance and Java/objective-C style interfaces) in the examples subdirectory.

Some guidelines

Constructors

Destructor

Internal operation

Some notes on the internal operation:

• Static and normal (not virtual) methods are bound directly to the corresponding function call. The object is autmatically converted, i.e. the call switches to the appropriate base class (the class where to method was defined or last attached when redefining normal/static methods). This automatic conversion does not short-cut any type checking.
• Virtual methods use a vtbl for their dispatching. The object is again autmatically converted, i.e. the call switches to the appropriate base class, i.e. the class where to method was last attached.
• Virtual methods known only from their interface use dynamic binding for their dispatching. Type checking on the object is however short-cutted. The remaining arguments are still fully type-checked.

Naming conventions:

• item names with on ore more '__' in it are reserved for internal use
• class and method dependent items have names of the following format:
  prefix__class__method
• class dependent but method independent items have names of the following format:
  prefix__class
• class and method independent items have names of the following format:
  prefix__
• 'prefix' does not contain a '__' (nor does it end with a '_') and prefix follows the normal spraak rules, i.e. dependent on the item type, prefix starts with 'spr_', 'SPR_', 'Spr', ...)

Automatically generated types, variables and defines:

SprRTTI__class__method

typedef function pointer for each method (static of virtual); used by SprMethodPtr()

SprRTTI__class spr_rttid__class,spr_rttis__class;

typedef + variable: the run-time information contains run-time type information and the virtual functions dispatch table; the structure mimics the hierarchical structure of the class (base classes)

const char spr_rtti_mid__class__method[]

unique name of the method (given the class in which the method was defined)

const char spr_rtti_cid__class[]

unique name of the class

const char *const *spr_rtti_method__class[]

array containing the names of the virtual methods

SPR_DO__class__method

macro that does that provides the necessary information for the combination of class and method for SPR_DO(), SPR_DO_FPTR() and SPR_DO_OPTR()

SPR_CAST__class__base

macro that does that actual combination of class and base for SPR_CAST()

SPR_INIT__class

macro that does the actual initialisation; used by SPR_OBJECT_INIT() and SPR_LVAR_OBJECT_INIT()

Planned extensions:

SPR_DYNCAST(object,class_id)

cast the type of the object to the class with the given class id; this is a slow function; returns NULL if the cast fails

SPR_CLASSID_FROM_OBJ(object)

get the id (a pointer to a unique string) of the class the object belongs to

SPR_CLASSID_FORM_CLASS(class)

get the id (a pointer to a unique string) for the given class

SPR_OBJ_ISINSTANCE_OF(object,class_id)

check if the object can be casted the class with the given id; is a slow function

SPR_OBJ_DYN_ROOT(object)

convert the object to its root object (go all the way up in the hierarchy)