MDI (Method Dictionary)

The Method Dictionary describes the methods of a class visible to InstantView®. C++ code is generated from a formalised description by means of the ClassiX® program CXDGEN. The description contains:

Return value	generalised data type
Function name
Parameter 1	generalised data type
parameter2	generalised data type
. . .
Parameter n	generalised data type

where the following (generalised) data types exist:

Type	C++ - spelling	Comment	Footnote
VOID	void
STRING	char *
MULTIPLE_STRING	CXB_MULTIPLE_STRING * or CXB_MULTIPLE_STRING &
OBJECT	CX_CLASS * or CX_CLASS &
VOLATILE_OBJECT	CX_CLASS * or CX_CLASS &	only as return value	1.
VECTOR<OBJECT>	CX_CLASS **	last element NULL
VECTOR<INTEGER>	int *	last element INT_MAX
VECTOR<STRING>	char **	last element NULL
COLLECTION	os_collection * or os_collection &
MA	CXS_VIEW_DESCRIPTOR *	only as first parameter	2.
ANY	void *	only as return value	3.

1. If a function creates a transient object, you can request that the garbage collection of the ClassiX® system automatically removes this object as soon as it is no longer needed. This is done by entering VOLATILE_OBJECT as return value for the function.
2. for one access function; other 'normal' parameters may follow.
3. Functions that return data of different types for different calls can be entered with signature ANY. The function must make the type of the return value known to the ClassiX® system with CX_CLASS::SetTypeOfReturnValue(); tables for implicit transformation of enumerations can be registered by the function with CX_CLASS::RegisterEnumTransTbl(). This feature is used e.g. for attributes (objects of classes derived from CX_ATTRIBUTE).

Example: