[cctbxbb] Boost.Extension plugins in CCTBX

[Luc Bourhis]

Hi Graeme,

> What about if it needed compiled code? For example a new compression scheme? Then they would need to make some quite substantial changes I would think.

I would naively do it as we have always done it: create a new Boost Python extension implementing the new compression scheme, then tweak the Python code to decide when to use that new scheme and when to use the old one. The Python tweak will typically be insignificant an amount of work compared to what will be sunk into implementing the compression scheme in C++. The latter won't be reduced by the technology you advocate, will it? 

> Also if we (for performance reasons) were working in C++ with the image handling adding the Python code like that would be less helpful.

Pure C++ applications should have a very hard time to use the iotbx anyway as many of the key objects are Python-only (xray.structure, miller.array, etc).

Best wishes,

Luc