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DispInvoke

Windows Mobile 6.5
A version of this page is also available for
4/8/2010

This function automatically calls member functions on an interface, given the type information for the interface.


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 
);

_this

[in] Pointer to an implementation of the IDispatch interface described by ptinfo.

ptinfo

[in] Pointer to the type information that describes the interface.

dispidMember

[in] Identifies the member.

Use IDispatch::GetIDsOfNames or the object's documentation to obtain the DISPID.

wFlags

[in] Flags describing the context of the Invoke call, as follows.

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.

pparams

Pointer to a structure that contains the following:

  • An array of arguments
  • An array of argument DISPIDs for named arguments
  • Counts for number of elements in the arrays
pvarResult

[out] Pointer to where the result is to be stored, orNULL if the caller expects no result.

This argument is ignored if DISPATCH_PROPERTYPUT or DISPATCH_PROPERTYPUTREF is specified.

pexcepinfo

[out] Pointer to a structure that contains exception information.

This structure should be filled in if DISP_E_EXCEPTION is returned.

puArgErr

[out] Index within rgvarg of the first argument that has an error.

Arguments are stored in pdispparams->rgvarg in reverse order, so the first argument is the one with the highest index in the array.

This parameter is returned only when the resulting return value is DISP_E_TYPEMISMATCH or DISP_E_PARAMNOTFOUND.

Returns the HRESULT values shown in the following table.

Value Description

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

An argument 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

An argument in DISPPARAMS could not be coerced to the specified type.

DISP_E_PARAMNOTFOUND

A parameter ID 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 arguments could not be coerced.

The index of the first parameter with the incorrect type within rgvarg is returned in puArgErr.

E_INVALIDARG

An argument is invalid.

E_OUTOFMEMORY

Insufficient memory to complete the operation.

Other return codes

Any ITypeInfo::Invoke error can 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.

Passing invalid (and under some circumstances NULL) pointers to this function causes an unexpected termination of the application.

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); 
}

Headeroleauto.h
Libraryoleaut32.lib
Windows Embedded CEWindows CE 2.0 and later
Windows MobileWindows Mobile Version 5.0 and later

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