Version 9 of unload

unload ?switches? fileName ?packageName? ?interp?

Eventually, the doc should appear here: http://www.purl.org/tcl/home/man/tcl8.5/TclCmd/unload.htm

New command in Tcl 8.5. See TIP 100 [L1 ] from George Petasis for where it came from.

Hints for extension authors who want to have an unloadable extension:

Be prepared for extra work when using a custom Tcl_Object type with non-NULL freeProc
Be extremly careful in your use of TSD (Thread Specific Data)
Be prepared for trouble if your extension involves the VFS layer
...

JH: Note that TIP 239 [L2 ] will likely change the unload command before 8.5 is final.

RS 2007-10-19: Here's a simple working example of building a DLL with tcltcc, loading, calling, unloading it:

 #!/usr/bin/env tclsh85

 package require tcc 0.2
 set d [tcc::dll]
 $d ccode {static int fib(int n) {return n <= 2? 1 : fib(n-1) + fib(n-2);}}
 $d cproc fiboy {int n} int {return fib(n);}
 $d cproc hello {} char* {return "world";}
 $d ccode {
    DLL_EXPORT int Fiboy_Unload(Tcl_Interp* interp, int flags) {
        Tcl_DeleteCommand(interp,"fiboy");
        Tcl_DeleteCommand(interp,"hello");
        printf("bye, world! flags: %d\n", flags);
        return TCL_OK;
    }
 }
 $d write -name fiboy -code {Tcl_Eval(interp,"puts {hello Fiboy!}");}

 load fiboy[info sharedlibextension]
 puts "[fiboy 20] [hello]"

 unload fiboy[info sharedlibextension]
 catch {puts "[fiboy 20] [hello]"} res
 puts $res

Only if a _Unload function is provided (_SafeUnload for safe interps) will unload succeed. Be careful to delete all commands the DLL created, otherwise get a seg fault.

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