ITypeInfo::Invoke Function

Invokes a method, or accesses a property of an object, that implements the interface described by the type description.

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HRESULT Invoke(  
  VOID FAR  *pvInstance,     
  MEMBERID  memid,           
  unsigned short  wFlags,    
  DISPPARAMS FAR  *pDispParams,  
  VARIANT FAR  *pVarResult,  
  EXCEPINFO FAR  *pExcepInfo,  
  unsigned int FAR  *puArgErr  
);

pvInstance

Pointer to an instance of the interface described by this type description.

memid

Identifies the interface member.

wFlags

Flags describing the context of the invoke call, as follows:

Value

Description

DISPATCH_METHOD

The member is accessed as a method. If there is ambiguity, 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 using a reference assignment, rather than a value assignment. This value is only valid when the property accepts a reference to an object.

pDispParams

Points to a structure that contains an array of arguments, an array of DISPIDs for named arguments, and counts of the number of elements in each array.

pVarResult

Should be Null if the caller does not expect any result. Otherwise, it should be a pointer to the location at which the result is to be stored. If wFlags specifies DISPATCH_PROPERTYPUT or DISPATCH_PROPERTYPUTREF, pVarResultis ignored.

pExcepInfo

Points to an exception information structure, which is filled in only if DISP_E_EXCEPTION is returned. If pExcepInfois Null on input, only an HRESULT error will be returned.

puArgErr

If Invoke returns DISP_E_TYPEMISMATCH, puArgErr indicates the index (within rgvarg) of the argument with incorrect type. If more than one argument returns an error, puArgErr indicates only the first argument with an error. Arguments in pDispParams->rgvarg appear in reverse order, so the first argument is the one having the highest index in the array. Cannot be Null.

The return value obtained from the returned HRESULT is one of the following:

Return value

Meaning

S_OK

Success.

E_INVALIDARG

One or more of the arguments is invalid.

DISP_E_EXCEPTION

The member being invoked has returned an error HRESULT. If the member implements IErrorInfo, details are available in the error object. Otherwise, the pExcepInfoparameter contains details.

Other return codes

Any of the IDispatch::Invoke errors may also be returned.

Use the function ITypeInfo::Invoke to access a member of an object or invoke a method that implements the interface described by this type description. For objects that support the IDispatch interface, you can use Invoke to implement IDispatch::Invoke.

ITypeInfo::Invoke takes a pointer to an instance of the class. Otherwise, its parameters are the same as IDispatch::Invoke, except that ITypeInfo::Invoke omits the refiid and lcid parameters. When called, ITypeInfo::Invoke performs the actions described by the IDispatch::Invoke parameters on the specified instance.

For VTBL interface members, ITypeInfo::Invoke passes the LCID of the type information into parameters tagged with the lcid attribute, and the returned value into the retval attribute.

If the type description inherits from another type description, this function recurses on the base type description to find the item with the requested member ID.

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