Date: 06.05.15 - 7:38pm
I have been tinkering with a new project, to try and get the dukTape js engine working with visual basic six. My end goal hopefully would be similar to what I did with script basic.
So how do we map an arbitrary number and prototypes of functions and wire them into the correct method on the COM object.
When you call AddObject in the Microsoft script control, it has to use the typelib information to extract all of the prototypes to know how to call them. Ok I have done this.
in the duktape C api you can create arbitrary objects and methods on them..but they are designed to each call a specific C function. This wont work for what I am trying.
Here is what I came up with so far. it is working, but will be further refined.
I added a single native C function called resolver.
Now in vb6 I can do the following (all testing and working so far) to make alert() work I rewired the DUK_FWRITE to redirect to my own stdout handler which calls back to vb6
rv = Eval("1+2") 'works rv = Eval("alert(1+2)") 'works rv = Eval("pth = cmndlg.ShowOpen(4,'title','c:\',0); alert(fso.ReadFile(pth))") 'works rv = Eval("form.caption = 'test!'; alert(form.ReadFile('c:\lastGraph.txt'));") rv = Eval("form.caption = 'test!';alert(form.caption)")
So everything is looking good so far. property gets and sets are functional as are arbitrary method calls. To make the magic work my vb host resolver function
Before I goto much farther down that road which will be a lot of work though..I think I will start experimenting with the debugger capabilities (here and here) to make sure I can control it.
One more thing to resolve..right now all the COM objects and methods I have tested are on static global top level objects. What if a method returns a new object instance such as with the Microsoft Scripting runtime or Excel automation? ex:
Function OpenTextFile(FileName As String, [IOMode As IOMode = ForReading], [Create As Boolean = False], [Format As Tristate = TristateFalse] ) As TextStream Function ReadAll() As String Member of Scripting.TextStream
how to call a method on a specific instance of an object instead of static top level global objects like we have been? My first thought was to add a int field to the TextStreamClass of my own that would hold an objptr(obj) to identify it uniquely. Resolver will have to return a new class instance, and set say a hInst field of it. Thanks to some help from the guys on the IRC channel this is already working in a simple test scenario ex:
duk_get_global_string(ctx, "fsoClass"); duk_new(ctx, 0);
Also looking at the debugger docs, they are marked as highly experimental. My instinct is telling me to hold off on messing with the debugger side of it for a bit just in case.