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2.2.49.3 Automation-Compatible Types

  • Article

The OLE Automation Protocol restricts the types of parameters that can be used in the definition of an automation interface (see section 2.2.49.4). 

 type-attribute = rpc-defined / 
             uuid-attr / 
             help-attr /
             custom-attr /
             kw-public /
             kw-restricted
  
 oa-type-spec =  oa-base-type-spec /
     oa-safearray-type-spec /
     oa-ptr-type-spec /
     Identifier
  
 oa-base-type-spec = oa-base-nondecimal-type-spec / kw-Decimal
  
 oa-base-nondecimal-type-spec =  kw-boolean /
     [kw-unsigned] LWSP kw-char  /
     [kw-unsigned] LWSP kw-short /
     [kw-unsigned] LWSP kw-int   /
     [kw-unsigned] LWSP kw-long  /
     kw-double   /
     kw-float    /
     kw-BSTR     /
     kw-CURRENCY /
     kw-DATE     /
     kw-SCODE
  
 oa-safearray-type-spec  = 
     kw-SAFEARRAY "(" oa-base-nondecimal-type-spec ")" /
     kw-SAFEARRAY "(" oa-ptr-type-spec ")" /
     kw-SAFEARRAY "(" Identifier ")"
  
 oa-ptr-type-spec =  oa-base-nondecimal-type-spec "*" /
     oa-safearray-type-spec "*" /
     Identifier "*"
  
 

In the preceding productions, <Identifier> MUST be a type that is defined as an enumeration type, a UDT, or an automation-compatible interface (see section 2.2.49.4.1 for details).

The restriction that defines the automation-compatible types is that they MUST be representable as a field in a VARIANT (section 2.2.29.2).

The following table specifies the mapping between the IDL keyword and the associated VARIANT type constant (see section 2.2.7) that MUST<37> be used when storing the type in a VARIANT. These are the only types that are legal in an automation-compatible interface (see section 2.2.49.4.1).

Type keyword

VARIANT type constant

boolean

VT_BOOL

unsigned char

VT_UI1

char

VT_I1

double

VT_R8

float

VT_R4

unsigned int

VT_UI4

int

VT_I4

unsigned long

VT_UI4

long

VT_I4

unsigned short

VT_UI2

short

VT_I2

BSTR

VT_BSTR

CURRENCY

VT_CY

VARIANT

VT_BYREF|VT_VARIANT

DATE

VT_DATE

Decimal

VT_DECIMAL

SCODE

VT_ERROR

HRESULT

VT_ERROR

typedef enum myenum

VT_I4

typedef struct myUDT

VT_RECORD or

VT_BYREF|VT_RECORD

interface IDispatch*

VT_DISPATCH

interface IUnknown*

VT_UNKNOWN

dispinterface Typename*

VT_DISPATCH

[oleautomation] interface Typename*

VT_UNKNOWN

SAFEARRAY(Typename)

VT_ARRAY

Typename*

VT_BYREF | the variant type associated with Typename

[dual] interface Typename*

VT_DISPATCH

The methods of an Automation Interface Definition Language (AIDL) interface MUST return an HRESULT or SCODE. The methods and properties of an ODL dispinterface MUST return only the types that are specified in the previous table. Otherwise, an automation interface MUST use types from the previous table. See AIDL Interfaces and ODL Dispinterfaces (section 2.2.49.7) for more information.

uuid-attr: Specifies a GUID that MUST identify the type. Any automation-compatible constructed types (enums, structs, or unions) that are not declared with a specifying GUID cannot be retrieved using ITypeLib::GetTypeInfoOfGuid (section 3.11.4.4).

help-attr: Specifies information associated with the type that can be retrieved using ITypeLib::GetDocumentation (section 3.11.4.7) or ITypeInfo::GetDocumentation (section 3.7.4.8).

kw-public: Specifies that the element is an alias declared with the typedef keyword and explicitly included in an automation scope.

kw-restricted: Specifies that the element is not intended to be used under all conditions. Type browser clients MAY<38> place restrictions on the visibility or usability of elements that have this attribute. Elements with the [restricted] attribute MUST NOT also have the [default] attribute.

kw-hidden: Specifies that the type is not intended to be displayed to users. Type browser clients SHOULD NOT expose the functionality of elements that have this attribute.