How getObject Function internally works?

Question

I\'m Automating Inventor 2013 using UFT as follows:-

Set oApp = GetObject(,\"Inventor.Application\") Set oDoc = oApp.ActiveDocument

Here I

Answer 1

You turn off error checking, attempt a GetObject and then test err.number <> 0. If inventor is running the call will succeed and err.number will be 0, else it will be 424 error (I think).

The API calls made for each variant of the GetObject are detailed at https://msdn.microsoft.com/en-us/library/windows/desktop/ms221192(v=vs.85).aspx.

From above link.

GetObject (filename, ProgID)

CLSIDFromProgID 

CoCreateInstance 

QueryInterface for IPersistFile interface.

Load on IPersistFile interface.

QueryInterface to get IDispatch interface. 

GetObject (filename)

CreateBindCtx creates the bind context for the subsequent functions.

MkParseDisplayName returns a moniker handle for BindMoniker.

BindMoniker returns a pointer to the IDispatch interface.

Release on moniker handle.

Release on context.

GetObject (ProgID)

CLSIDFromProgID 

GetActiveObject on class ID.

QueryInterface to get IDispatch interface. 

You can look up each individual function call here

https://msdn.microsoft.com/en-us/library/windows/desktop/ms680586(v=vs.85).aspx

EG

CLSIDFromProgID function

Looks up a CLSID in the registry, given a ProgID.

Syntax

HRESULT CLSIDFromProgID(
  _In_  LPCOLESTR lpszProgID,
  _Out_ LPCLSID   lpclsid
);