[GNC-dev] Python: About Wrapping SWIG Objects (GncNumeric)

[c.holtermann at gmx.de]

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 
> example
> 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.
>> 
>> Christoph,
>> 
>> The person who wrote the first two lines of that, Mark Jenkins, was 
>> the
>> 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 
>> the
>> python bindings. Your history with them is almost as long as his--in 
>> fact
>> 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 
>> that
>> 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
>> SWIG.
>> 
> It would be a very useful experiment to wrap the C++ GncNumeric class 
> directly
> rather than it's c wrapper gnc_numeric_xxx. Python doesn't need the c
> compatibility layer it represents.
> 
> Geert

Geert,

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 
would
be a good candidate. I'll have a look at it. Thanks for the blessing :-)

have a nice day !

Christoph