Caché ObjectScript Reference
Loads a Dynamic-Link Library (DLL) and executes a library function.
||The name of the dynamic-link library (DLL) to load, specified as a quoted string. When a DLL is already loaded, dll_name can be specified as a null string ("").
||Optional The name of the function to execute within the DLL, specified as a quoted string.
||Optional A comma-separated list of arguments to pass to the function.
to load a Dynamic-Link Library (DLL) and execute the specified function from that DLL. $ZF(-3)
returns the function’s return value.
can be invoked in any of the following ways:
To load a DLL and execute a function located in that DLL:
Loading a DLL using $ZF(-3)
makes it the current DLL, and automatically unloads the DLL loaded by a previous invocation of $ZF(-3)
To execute a function located in a DLL loaded by a previous $ZF(-3)
, you can speed execution by specifying the current DLL using the null string, as follows:
To explicitly unload the current DLL (loaded by a previous $ZF(-3)
can load only one DLL. Loading a DLL unloads the previous DLL. You can also explicitly unload the currently loaded DLL, which would result in no currently loaded DLL. (However, note that $ZF(-3)
loads and unloads do not affect loads and unloads for use with $ZF(-5)
, as described below.)
The DLL name specified can be a full pathname, or a partial pathname. If you specify a partial pathname, Caché canonicalizes it to the current directory. Generally, DLLs are stored in the binary directory (bindir). To locate the binary directory, call the BinaryDirectory()
method of the %SYSTEM.Util
class. For further details, refer to the InterSystems Class Reference
A DLL is a binary library that contains routines that can be loaded and called at runtime. When a DLL is loaded, Caché finds a function named GetZFTable()
within it. If GetZFTable()
is present, it returns a pointer to a table of the functions located in the DLL. Using this table, $ZF(-3)
calls the specified function from the DLL.
Calls to $ZF(-3)
can only load one DLL at a time; loading a DLL unloads the previous DLL. To load multiple DLLs concurrently, execute DLL functions with $ZF(-5)
. Loading or unloading a DLL using $ZF(-3)
has no effect on DLLs loaded for use with $ZF(-5)