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Hello John,</div>
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I have submitted a PR (<a href="https://github.com/Gnucash/gnucash/pull/2066" id="LPlnk951583">https://github.com/Gnucash/gnucash/pull/2066</a>). I added type translators for all the types that were supported by the typemap(out) for GList but have only
tested with lists of GncLot objects, as I am not sure where to find existing C functions that take some of the other types of lists. This at least fixes the issue with Customer.ApplyPayment not working at all from Python.</div>
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Thanks,</div>
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Oliver Trevor</div>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> John Ralls <jralls@ceridwen.us><br>
<b>Sent:</b> Saturday, March 8, 2025 11:26 PM<br>
<b>To:</b> Oliver Trevor <olt@mit.edu><br>
<b>Cc:</b> gnucash-devel@gnucash.org <gnucash-devel@gnucash.org><br>
<b>Subject:</b> Re: Issues with GList Arguments in Python Bindings?</font>
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<div>On Mar 8, 2025, at 14:57, Oliver Trevor <olt@mit.edu> wrote:</div>
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Hello Gnucash developers,</div>
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I was attempting to use the Gnucash Python bindings to apply payments to a list of invoices using Customer.ApplyPayment (which maps to gncOwnerApplyPaymentSecs on the C side), but it gives an error "TypeError: in method 'gncOwnerApplyPaymentSecs', argument
3 of type 'GList *'" when I attempt to pass a Python list of lots as the second argument "lots" (third argument on the C side).</div>
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Looking at how the SWIG bindings were written, I think the issue may be that there is not a type translator that turns Python lists into GList. base-typemaps.i has a SWIG type translator on line 269 that converts Python lists into GSList objects, but as
far as I can tell there isn't one that converts Python lists into GList objects.</div>
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Am I correct that this is an issue, or am I missing how the bindings are intended to be used? If it's an issue, I could work on a PR to add a type translator for GList. Also, has anybody ever tried making bindings using GObject introspection instead of
SWIG, since Gnucash's API is already GLib-based?</div>
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<div>Oliver,</div>
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<div>Looks to like you’re right. There are several SCM List <-> GList* typemaps but only a typemap(out) for Python, not useful for passing arguments into a C function. Go ahead and write a PR.</div>
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<div>I don’t think anyone has considered GI. While somebody made a start on GI bindings for Guile (<a href="https://github.com/spk121/guile-gi">https://github.com/spk121/guile-gi</a>) it’s a fairly recent (started in 2019) project and seems to have been abandoned
a couple of years ago. Meanwhile on the GnuCash side while it’s true that we have GObject-based classes, their memory management wasn’t done correctly and probably wouldn’t integrate well with GI. Our long-term goal is to reimplement them as C++ objects.</div>
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<div>Regards,</div>
<div>John Ralls</div>
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