HRESULT DispInvoke(
void FAR* _this,
ITypeInfo FAR* ptinfo,
DISPID dispidMember,
unsigned short wFlags,
DISPPARAMS FAR* pparams,
VARIANT FAR* pvarResult,
EXCEPINFO pexcepinfo,
unsigned int FAR* puArgErr
);
Automatically calls member functions on an interface, given the type information for the interface. You can describe an interface with type information and implement IDispatch::Invoke for the interface using this single call.
Value | Description |
---|---|
DISPATCH_METHOD | The member is invoked as a method. If a property has the same name, both this and the DISPATCH_PROPERTYGET flag can be set. |
DISPATCH_PROPERTYGET | The member is retrieved as a property or data member. |
DISPATCH_PROPERTYPUT | The member is changed as a property or data member. |
DISPATCH_PROPERTYPUTREF | The member is changed by a reference assignment, rather than a value assignment. This flag is valid only when the property accepts a reference to an object. |
The return value obtained from the returned HRESULT is one of the following:
Return value | Meaning |
---|---|
S_OK | Success. |
DISP_E_BADPARAMCOUNT | The number of elements provided in DISPPARAMS is different from the number of arguments accepted by the method or property. |
DISP_E_BADVARTYPE | One of the arguments in DISPPARAMS is not a valid variant type. |
DISP_E_EXCEPTION | The application needs to raise an exception. In this case, the structure passed in pexcepinfo should be filled in. |
DISP_E_MEMBERNOTFOUND | The requested member does not exist. |
DISP_E_NONAMEDARGS | This implementation of IDispatch does not support named arguments. |
DISP_E_OVERFLOW | One of the arguments in DISPPARAMS could not be coerced to the specified type. |
DISP_E_PARAMNOTFOUND | One of the parameter IDs does not correspond to a parameter on the method. In this case, puArgErr is set to the first argument that contains the error. |
DISP_E_PARAMNOTOPTIONAL | A required parameter was omitted. |
DISP_E_TYPEMISMATCH | One or more of the arguments could not be coerced. The index of the first parameter with the incorrect type within rgvarg is returned in puArgErr. |
E_INVALIDARG | One of the arguments is invalid. |
E_OUTOFMEMORY | Insufficient memory to complete the operation. |
Other return codes | Any of the ITypeInfo::Invoke errors can also be returned. |
The parameter _this is a pointer to an implementation of the interface that is being deferred to. DispInvoke builds a stack frame, coerces parameters using standard coercion rules, pushes them on the stack, and then calls the correct member function in the VTBL.
The following code from the Lines sample file Lines.cpp implements IDispatch::Invoke using DispInvoke. This function uses m_bRaiseException
to signal that an error occurred during the DispInvoke call.
STDMETHODIMP
CLines::Invoke(
DISPID dispidMember,
REFIID riid,
LCID lcid,
WORD wFlags,
DISPPARAMS FAR* pdispparams,
VARIANT FAR* pvarResult,
EXCEPINFO FAR* pexcepinfo,
UINT FAR* puArgErr)
{
return DispInvoke(
this, m_ptinfo,
dispidMember, wFlags, pdispparams,
pvarResult, pexcepinfo, puArgErr);
}
Windows NT: Use version 3.1 and later.
Windows: Use Windows 95 and later.
Header: Declared in oleauto.h.
Import Library: Link with oleaut32.lib.
CreateStdDispatch, IDispatch::Invoke