Patches to integrate adslib directly into pyads

[stlehmann]

Hi there,

I'm the author and maintainer of pyads – a Python wrapper around adslib that gained some popularity. It uses ctypes to call into the library. It's basically the glue between the Python world and the ADS protocol.

Currently, pyads relies on a fork of adslib that I have to maintain separately, which is becoming a bit of a burden to keep in sync with upstream. So I had an idea that might make things cleaner for both sides:

What if adslib was integrated directly from upstream into pyads?

The required changes on the adslib side would be manageable:

• Wrapping the relevant functions in extern "C" { ... } to prevent C++ name mangling – this is a hard requirement for ctypes to be able to resolve and call the exported functions
• Building adslib as a shared library (.so ) in addition to the existing static library

That way pyads could link against a proper upstream build instead of carrying around its own patched copy – and every update to adslib would just flow through automatically. No more fork drift.

Happy to discuss and help with the implementation if there is interest.

[pbruenn]

Hi @stlehmann,
of course I remember you. Thanks for reaching out again.

Yes, I think the time has come for a dynamically linked version. Adding extern "C" to the required functions shouldn't be an issue and we can add the shared library as an additional build target.

I took a quick look at https://github.com/stlehmann/ADS/tree/master to see what you needed to change, but there is some noise from CRLF lineendings I guess.

One thing I remember from the past is a decision that has been haunting me ever since: https://github.com/Beckhoff/ADS/blob/master/AdsLib/standalone/AdsDef.h#L409-L418

We would need to revisit this to align with the TwinCAT SDK. My original reasoning was that this library is statically linked and that the structure only forms a contract between the library and the enclosing application, so reordered the members to be size aligned. Well, I guess I put it into a precompiler flag to choose aligned vs. twincat style and everybody should be fine.

For the build and release, I’d appreciate any help. I’m more of a GitLab person and not a big fan of GitHub Actions—I’ve mostly had trouble with them, especially when the versions of the actions change.

Could you provide a cleaned up branch with only the necessary changes we need?

Thanks,
Patrick

[stlehmann]

@pbruenn that sounds great. Thanks for your quick reply.

I will provide a branch that implements the necessary changes so we will have a better overview.
Also I might be able to help with some Github Action issues if necessary. Had to ninja through this lately myself ;)

Regards,
Stefan