`pyconvert_add_rule` must be executed before using `pyimport` in `__init__()`

[johroj]

Affects: PythonCall

Description:

It took me ages to figure out why the following did not manage to add a conversion rule, despite it following the documentation here and here

const mylib = pynew()
function __init__()
    pycopy!(mylib, pyimport("mylib")
    pyconvert_add_rule(".......", T, _func)
end

It seems swapping the order solves the issue

const mylib = pynew()
function __init__()
    pyconvert_add_rule(".......", T, _func)
    pycopy!(mylib, pyimport("mylib")
end

i.e. the conversion rule must be added before pyimport is called. I guess it is too late to add the rules once the python executable has started? Perhaps this should be clarified in the documentation?

[cjdoris]

No that's a bug, you should be able to add rules at any point. What version of PythonCall are you on? Please post some complete reproducing code which demonstrates the issue.

[johroj]

I am certain I verified the bug multiple times before filing the bug report, but I cannot reproduce the issue, unfortunately.

[cjdoris]

Thanks for closing. I have some vague recollection that we fixed a bug a while back to do with cacheing these conversion rules - maybe that fixed your issue.