Valid Types
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In the Type Library editor, you use different type identifiers, depending on whether you are working in IDL or Delphi. Specify the language you want to use in the Environment options dialog.
The following types are valid in a type library for COM development. The Automation-compatible column specifies whether the type can be used by an interface that has its Automation or Dispinterface flag checked. These are the types that COM can marshal via the type library automatically:
| Delphi type | IDL type | Variant type | Automation compatible | Description |
|---|---|---|---|---|
|
Smallint |
short |
VT_I2 |
Yes |
2-byte signed integer |
|
Integer |
long |
VT_I4 |
Yes |
4-byte signed integer |
|
Single |
single |
VT_R4 |
Yes |
4-byte real |
|
Double |
double |
VT_R8 |
Yes |
8-byte real |
|
Currency |
CURRENCY |
VT_CY |
Yes |
currency |
|
TDateTime |
DATE |
VT_DATE |
Yes |
date |
|
WideString |
BSTR |
VT_BSTR |
Yes |
binary string |
|
IDispatch |
IDispatch |
VT_DISPATCH |
Yes |
pointer to IDispatch interface |
|
SCODE |
SCODE |
VT_ERROR |
Yes |
Ole Error Code |
|
WordBool |
VARIANT_BOOL |
VT_BOOL |
Yes |
True = -1, False = 0 |
|
OleVariant |
VARIANT |
VT_VARIANT |
Yes |
Ole Variant |
|
IUnknown |
IUnknown |
VT_UNKNOWN |
Yes |
pointer to IUnknown interface |
|
Shortint |
byte |
VT_I1 |
No |
1 byte signed integer |
|
Byte |
unsigned char |
VT_UI1 |
Yes |
1-byte unsigned integer |
|
Word |
unsigned short |
VT_UI2 |
Yes* |
2-byte unsigned integer |
|
LongWord |
unsigned long |
VT_UI4 |
Yes* |
4-byte unsigned integer |
|
Int64 |
__int64 |
VT_I8 |
No |
8-byte signed integer |
|
Largeuint |
uint64 |
VT_UI8 |
No |
8-byte unsigned integer |
|
SYSINT |
int |
VT_INT |
Yes* |
system dependent integer (Win32=Integer) |
|
SYSUINT |
unsigned int |
VT_UINT |
Yes* |
system-dependent unsigned integer |
|
HResult |
HRESULT |
VT_HRESULT |
No |
32-bit error code |
|
Pointer |
VT_PTR -> VT_VOID |
No |
untyped pointer | |
|
SafeArray |
SAFEARRAY |
VT_SAFEARRAY |
No |
OLE Safe Array |
|
PAnsiChar |
LPSTR |
VT_LPSTR |
No |
pointer to Char |
|
PChar |
LPWSTR |
VT_LPWSTR |
No |
pointer to WideChar |
|
PWideChar |
LPWSTR |
VT_LPWSTR |
No |
pointer to WideChar |
Note: Word, LongWord, SYSINT, and SYSUINT may be Automation-compatible with some applications.
See SafeArrays for more information about the SAFEARRAY Variant type.
Note: The Byte (VT_UI1) is Automation-compatible, but is not allowed in a Variant or OleVariant because many Automation servers do not handle this value correctly.
Besides these IDL types, any interfaces and types defined in the library or defined in referenced libraries can be used in a type library definition.
The Type Library editor stores type information in the generated type library (.TLB) file in binary form.
If a parameter type is specified as a Pointer type, the Type Library editor usually translates that type into a variable parameter. When the type library is saved, the variable parameter's associated ElemDesc's IDL flags are marked IDL_FIN or IDL_FOUT.
Often, ElemDesc IDL flags are not marked by IDL_FIN or IDL_FOUT when the type is preceded with a Pointer. Or, in the case of dispinterfaces, IDL flags are not typically used. In these cases, you may see a comment next to the variable identifier such as {IDL_None} or {IDL_In}. These comments are used when saving a type library to correctly mark the IDL flags.