[cctbxbb] boost python conversions help needed

Winter, Graeme (DLSLtd,RAL,LSCI) Graeme.Winter at diamond.ac.uk
Wed Sep 30 13:50:00 PDT 2020

Hi Gabor,

Thanks for this - seems you’re on the right track here & by commenting out


the errors go away… now I need to figure what is aliasing uint32_t as a size_t is 64 bit … however this has now given me a hook into the mystery

Will look some more at this registry and what is going on in here…

Much thanks for this assistance!

All the best Graeme

On 30 Sep 2020, at 09:59, Gabor Bunkoczi <gabor.bunkoczi at googlemail.com<mailto:gabor.bunkoczi at googlemail.com>> wrote:

Hi Graeme,

I am not sure how useful this is going to be, but here are two strategies to deal with this scenario:

1. You can query the Python converter registry to see that a converter for a particular type has been registered, e.g. as it is done here:


This is useful when you want to export something with a particular name, but share the implementation with something pre-existing (e.g. size_t being uint64).

2. You can uniquify the types you are exporting, e.g. as it is done here :


This is useful when you want to export a unique list, but the uniqueness depends on e.g. the architecture, as for size_t.

Unfortunately, these are only useful when exports are centralised, as unconditional class_ statements will cause the same warning to be emitted.

BW, Gabor

On Wed, Sep 30, 2020 at 6:30 AM Winter, Graeme (DLSLtd,RAL,LSCI) <Graeme.Winter at diamond.ac.uk<mailto:Graeme.Winter at diamond.ac.uk>> wrote:

Does anyone know about this stuff or am I on my own here?

Alternative of using numpy arrays to do the job has been suggested but would prefer keeping in the cctbx ecosystem

Thanks Graeme

On 28 Sep 2020, at 07:15, Winter, Graeme (DLSLtd,RAL,LSCI) <graeme.winter at diamond.ac.uk<mailto:graeme.winter at diamond.ac.uk>> wrote:

Hi All,

In the branch


I am working to add a full range of fixed-width integer types to allow explicit reading of binary data without conversion from images (amongst other things) - mostly I’ve got something _working_ but tests fail because stdout / err contains

  Standard error:
    /Users/graeme/svn/cctbx/conda_base/python.app/Contents/lib/python3.6/importlib/_bootstrap.py:219: RuntimeWarning: to-Python converter for scitbx::af::shared<unsigned int> already registered; second conversion method ignored.

has anyone got any hints where these may be registered?

The details of the low level flex implementation seems to be minimally documented, and the error has no useful stack trace, so I am at a bit of a loss as to where the other unsigned int conversion is registered.

Some pointers from someone who has delved into these in the past would be welcome - I have spent a couple days trying to find what I am doing wrong and have so far failed - hopefully someone on the list knows their way around in here

Cheers Graeme


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