I had a little fun with chatgpt this week. C dll is a dynamic proxy that wraps an arbitrary inner COM object. Lets you override methods or add new methods to an existing object. Wanted this for a looongg time and chatgpt pulled if off with some coercion.
we are basically creating our own IDispatchEx interface in about 600 lines of pure C++ for languages which don't support it. Final release dll with /MT is about 130kb
C Dll debug messages are output to Elroys: http://www.vbforums.com/showthread.p...g-Print-Window
You can find a compiled copy and maybe more up to date source here:
https://github.com/dzzie/js4vb/tree/master/dynproxy
Note: more stuff has been added to this as js4vb grew such as a custom CallByNameEx and event sink code.
Readme below.
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# dynproxy — Dynamic COM Proxy for VB6 (and beyond)
> *The missing dynamic layer VB6 never had.*
> A raw C++ COM proxy that turns VB6 into a dynamic runtime.
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## What This Does
dynproxy.dll lets **VB6 (or any COM client)** create objects that respond to *any* property or method call dynamically — even ones that don’t exist.
It acts like a **programmable middle-man** between VB6 and COM:
- Intercepts every IDispatch::Invoke and GetIDsOfNames.
- Can forward to a real inner COM object or fake a response.
- Lets your **VB6 class** decide in real time what happens.
**No ATL. No MFC. Pure COM.**
---
## Why It Exists
No good reason..just a wish list
dynproxy fixes that: it lets you build **dynamic COM façades** that VB6 treats as real.
Now you can:
- Build **synthetic COM trees** (o.Kitty.Meow = 12).
- **Mock** sprawling APIs (Acrobat, Office, etc.).
- **Log or reroute** calls before they hit the real object.
- **Bridge** VB6 to scripting engines or remote APIs.
- Turn VB6 into something approaching Python or JavaScript’s Proxy.
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## How It Works
### The Proxy Pipeline
text
VB6 Runtime
(calls o.SomeMethod)
IDispatch::Invoke("SomeMethod")
ProxyDispatch
(dynproxy.dll)
1 Inner object Forward call
2 Resolver class
• Call VB6: ResolveGetID / ResolveInvoke
• Pass name, args, and DISPATCH_ flags
3 Neither Invent a DISPID and let resolver fake it
### Call Flow Details
1. **VB6** late-bound calls always go through IDispatch::Invoke.
2. The proxy catches that and checks a cache (name DISPID).
3. If unknown, it calls:
* inner->GetIDsOfNames() first (default), or
* resolver->ResolveGetID() first if resolver-wins mode is active.
4. The final Invoke routes accordingly:
* Forward to the inner COM object, **or**
* Call your resolver’s ResolveInvoke(name, flags, args()).
---
## VB6 Resolver Interface
Your resolver implements two public methods:
### flags meaningsCode:Public Function ResolveGetID(ByVal name As String) As Long
' Return non-zero to claim this name
' Return 0 to let the inner object handle it
End Function
Public Function ResolveInvoke(ByVal name As String, _
ByVal flags As Long, _
args() As Variant) As Variant
' Handle the call
End Function
| Flag | Hex | Meaning |
| ---- | --- | ------------------------------ |
| 1 | 0x1 | DISPATCH_METHOD (Sub/Function) |
| 2 | 0x2 | DISPATCH_PROPERTYGET |
| 4 | 0x4 | DISPATCH_PROPERTYPUT |
| 8 | 0x8 | DISPATCH_PROPERTYPUTREF |
---
## Example: Dynamic Tree
Demo:Code:' --- CResolver.cls ---
Option Explicit
Private m_children As Object, m_props As Object
Private Sub Class_Initialize()
Set m_children = CreateObject("Scripting.Dictionary")
Set m_props = CreateObject("Scripting.Dictionary")
End Sub
Public Function ResolveGetID(ByVal name As String) As Long
Select Case LCase$(name)
Case "kitty", "meow": ResolveGetID = -30000
Case Else: ResolveGetID = 0
End Select
End Function
Public Function ResolveInvoke(ByVal name As String, ByVal flags As Long, args() As Variant) As Variant
Dim lname As String: lname = LCase$(name)
' Property GET
If (flags And 2) <> 0 Then
If lname = "kitty" Then
If Not m_children.Exists("kitty") Then
Dim child As CResolver: Set child = New CResolver
Dim p As Long: p = CreateProxyForObjectRaw(0&, ObjPtr(child))
Dim o As Object: Set o = ObjectFromPtr(p)
m_children.Add "kitty", o
End If
Set ResolveInvoke = m_children("kitty"): Exit Function
End If
If m_props.Exists(lname) Then ResolveInvoke = m_props(lname)
Exit Function
End If
' Property PUT
If (flags And 4) <> 0 Then
m_props(lname) = args(0): Exit Function
End If
End Function
---Code:Dim root As New CResolver
Dim p As Long: p = CreateProxyForObjectRaw(0&, ObjPtr(root))
Dim o As Object: Set o = ObjectFromPtr(p)
o.kitty.meow = 12
Debug.Print o.kitty.meow ' 12
## Key Exports
All exports are stdcall, callable from VB6 directly.Code:| Function | Description |
| ---------------------------------------------------------- | ------------------------------------------------------ |
| CreateProxyForObjectRaw(inner, resolver) | Create proxy with an optional inner and resolver. |
| CreateProxyForObjectRawEx(inner, resolver, resolverWins) | Same, but choose resolver-first at creation. |
| SetProxyResolverWins(proxy, enable) | Toggle resolver-first mode at runtime. |
| ClearProxyNameCache(proxy) | Clear cached DISPIDs (call after toggling). |
| SetProxyOverride(proxy, name, dispid) | Force a name to route to resolver. |
| ReleaseDispatchRaw(ptr) | Manual release if you never wrapped the pointer in VB. |
---
## Build Notes
* **Language:** C++17
* **No** ATL or MFC
* **Link:** oleaut32.lib
* Build as **Win32 DLL**
cl /LD /std:c++17 dynproxy.cpp oleaut32.lib /EHsc /Fe:dynproxy.dll
## Why It’s Cool
* Intercepts and rewrites COM calls in real time.
* Lets VB6 behave like Python or JavaScript — dynamic and late-bound.
* Mocks any proprietary API instantly (no IDL hell).
* Enables powerful debugging, scripting, and adapter layers.
---
## Caveats
* Works only for **late-bound** (IDispatch) calls.
* STA threading only (standard VB6 COM).
* Don’t double-release VB6-wrapped objects.
* VB6 only runs 32-bit, so the DLL should be x86.
---
## * Credits & Origin
Implemented in pure C++ because ATL/MFC got in the way.
This project turns that pain into power — a *universal COM proxy* that lets old tech do new tricks.
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**Platform:** Win32 COM
**Language:** C++ / VB6
**Keywords:** VB6, COM, IDispatch, dynamic proxy, API mocking, automation, Acrobat
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