use 2 different versions of same control (dll) at the same time on same machine?

Question

Hi,

I'm using a3rd party component in my project and I recently upgraded to their latest version which fixed bug 'A'

unfortunately, while it solved bug 'A', another part has gotten completely unstable, so it introduced a bug 'B'.

Since 'A' and 'B' are in completely different contexts, I want to have both versions of the control installed and use the one in one case where bug 'B' is not relevant, and the other one in the case that bug 'A' is not relevant.

of course, everything until a proper fix has been issued by the 3rd party developer

Anyone any thought how this can be done?

R

p.s. the dll needs to be registered with regsvr32... I suspect this is the point where it makes itself findable... I'm hoping with some trickery it is here we can register the thing double under a different name

Answer 1

You can only register one COM dll of the same type on your machine... this is why the GAC is introduced by .Net

Answer 2

You can deploy different version of a COM component and use them without registration. This feature of registration-free COM has been introduced with Windows XP and requires you to deploy a .manifest file with the appropriate settings.

Have a look at Registration-Free Activation of COM Components and Escape DLL Hell: Simplify App Deployment with ClickOnce and Registration-Free COM.

Answer 3

If the third party component is a COM component, then you're on the right track, you need to register it twice using different names/Guids.

EDIT: see divo answer about multiple COM registration... After XP you can do this now...
But before that the only way to do this (short of having the source code and recompiling a new dll yourself with different registration guids), was to manually modify the type library, and replace the existing guids with new ones. This would be extremely difficult. (There may exist a tool to do this, but if there is I don;t know of it) The type library, by the way may be embedded in the dll itself, or it may be in a separate *.tlb file (common for VB6 components)

If, otoh, the component is a managed code component, then the registry may only be necessary for integration into visual studio, and it will be sufficient to just copy the dll into the application folder for the executable you are using it in...