CA_InvokeHelperV
HRESULT CA_InvokeHelperV (CAObjHandle objectHandle, ERRORINFO *errorInfo, int methodOrPropertyID, int operation, unsigned int returnType, void *returnValue, size_t parameterCount, unsigned int parameterTypes[], va_list parameterList);
Purpose
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Note This function has been superseded by CA_InvokeHelperVEx. The new function takes an additional parameter for interface id. Calling this function is equivalent to passing 0 for the interfaceId parameter. |
Gets or sets the value of an ActiveX server property or invokes a method of an ActiveX server. Unlike CA_InvokeHelper, CA_InvokeHelperV accepts arguments to the server operation as a variable argument list.
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Note This function is used by the functions generated by the ActiveX Controller Wizard. It is not intended to be used directly. |
Parameters
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| Name | Type | Description | ||||||||||
| objectHandle | CAObjHandle | An ActiveX object handle returned in an output parameter of an ActiveX server's function or a function in the Creating ActiveX Objects class in this library. | ||||||||||
| methodOrPropertyID | int | ID of the method or property you call or access; located in the server type library. | ||||||||||
| operation | int | Type of operation you want the server to perform. The operation parameter must be one of the values in the following table.
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| returnType | unsigned int | Type of the return value (if any). The value you pass for returnType depends on the operation parameter as shown in the following table.
You can use the CAVT_ARRAY modifier on all data types except CAVT_CSTRING and CAVT_OBJHANDLE. For parameters you pass by reference using DISPATCH_METHOD, you can use the CAVT_BYREFI, CAVT_BYREFO, or CAVT_BYREFIO modifier. For DISPATCH_PROPERTYPUTREF, you should add the CAVT_BYREFI modifier, but the ActiveX Library adds it for you if you forget. |
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| parameterCount | size_t | Number of arguments you pass that follow parameterTypes. The value you pass for parameterCount depends on the operation parameter as shown in the following table.
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| parameterTypes | unsigned int [] | Data types of each argument that follows this parameter. The value you pass for parameterTypes depends on the operation parameter as shown in the following table.
The parameterTypes array can contain any of the fundamental data types for variants, safe arrays, and properties except CAVT_NULL or CAVT_EMPTY. You can use the CAVT_ARRAY modifier on all data types except CAVT_CSTRING and CAVT_OBJHANDLE. For parameters you pass by reference using DISPATCH_METHOD, you can use the CAVT_BYREFI, CAVT_BYREFO, or CAVT_BYREFIO modifier. For DISPATCH_PROPERTYPUTREF, you should add the CAVT_BYREFI modifier, but the ActiveX Library adds it for you if you forget. |
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| parameterList | va_list | The arguments to the ActiveX server operation passed as a variable argument list initialized with the va_start macro. The number of arguments passed must match the count passed in the parameterCount parameter. The values you pass for parameters depends on the operation parameter as shown in the following table.
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| Output | ||||||||||||
| Name | Type | Description | ||||||||||
| errorInfo | ERRORINFO | When the ActiveX server method invoked by this function fails with the error code DISP_E_EXCEPTION, descriptive information about the error code is stored in this parameter. The descriptive information includes the error code, source, and description. The information also can include a help file and help file context. When the ActiveX server method invoked by this function fails with the error codes DISP_E_PARAMNOTFOUND, DISP_E_TYPEMISMATCH, or E_INVALIDARG, the parameter position of the invalid argument can be stored in the errorParamPos member of this parameter. This parameter can be NULL. |
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| returnValue | void * | The value (if any) the server method or property function returns. The value CA_InvokeHelper returns in returnValue depends on the operation parameter as shown in the following table.
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Return Value
| Name | Type | Description |
| status | HRESULT | A value indicating whether an error occurred. Function failure is indicated by a negative error code. Error codes are defined in CVIversion\include\cviauto.h and <Program Files>\National Instruments\Shared\MSDTRedistributables\SDKHeaderFiles\8.1\winerror.h. You can use CA_GetAutomationErrorString to get the description of an error code or CA_DisplayErrorInfo to display the description of the error code. If the error code is DISP_E_EXCEPTION (0x80020009 or -2147352567), then the errorInfo parameter contains additional error information. You can use CA_DisplayErrorInfo to display the error information. |
Additional Information
Library: ActiveX Library
Include file: cviauto.h
LabWindows/CVI compatibility: LabWindows/CVI 5.0 and later