[GNC-dev] Python: About Wrapping SWIG Objects (GncNumeric)
c.holtermann at gmx.de
c.holtermann at gmx.de
Mon Aug 6 10:43:58 EDT 2018
Am 2018-08-06 16:14, schrieb John Ralls:
>> On Aug 6, 2018, at 5:19 AM, c.holtermann at gmx.de wrote:
>> Am 2018-08-06 11:35, schrieb Geert Janssens:
>>> Op maandag 6 augustus 2018 05:32:27 CEST schreef John Ralls:
>>>> > On Aug 5, 2018, at 5:17 PM, c.holtermann at gmx.de wrote:
>>>> > Hello,
>>>> > after some time I get back to the gnucash python bindings.
>>>> > I worked on a str method for GncNumeric. It's in the example_script
>>>> > dir
>>>> > (https://github.com/Gnucash/gnucash/blob/maint/bindings/python/example_sc
>>>> > ripts/str_methods.py) I changed it to python3.
>>> I read at the beginning of this file you chose to implement it as an
>>> script which - if found useful - could be added to gnucash_core.
>>> You have my blessing to include it in gnucash_core :)
>>>> > Well I found it interesting to think these things through. Maybe someone
>>>> > can tell me about the mysterious "later on" in the cited comment. At this
>>>> > point I find it useful to have a way from the instance to the wrapping
>>>> > object through some kind of link as I suggested in the patch to
>>>> > function_class.
>>>> The person who wrote the first two lines of that, Mark Jenkins, was
>>>> original source of the Python bindings. He was never a regular dev,
>>>> he just
>>>> got 16 patches committed between 2007 and 2012, 10 of which touched
>>>> python bindings. Your history with them is almost as long as his--in
>>>> you have *12* commits--and pretty much no one else has done anything
>>>> serious with them.
>>> Hopefully Mark is still around on the list to clarify.
>>>> In other words, if anyone knows, it’s you!
>>> True :)
>>>> Just to add some more confusion, there’s now a C++ class GncNumeric
>>>> handles the actual implementation of many of the gnc_numeric.*
>>>> functions. I
>>>> believe that SWIG can’t see it, only the C wrapper functions are
>>>> exposed to
>>> It would be a very useful experiment to wrap the C++ GncNumeric class
>>> rather than it's c wrapper gnc_numeric_xxx. Python doesn't need the c
>>> compatibility layer it represents.
>> unfortunately your mail went to my spam folder for whatever reason.
>> Trying to
>> do C++ bindings for python sounds very interesting. I'd like to try
>> that when
>> I find the time for a simple example type. I don't know if GncNumeric
>> be a good candidate. I'll have a look at it. Thanks for the blessing
> Python has its own rational numbers so the only thing the Python
> bindings need is a way to convert to-and-from that to GncNumeric for
> communicating with the rest of the GnuCash API.
> I suggest QofSession as the first C++ class to play with SWIGing. It’s
> fairly simple and using it is the first step in using the bindings.
> John Ralls
Thanks for the suggestion. I'll also think about what you said about the
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