Guile API

[Peter Broadbery]

Hi Alex,

I've had a similar problem recenty - the begiin function is not
exported by engine.i, and I had to patch it in.  - see
https://github.com/pbroadbery/gnucash/commit/688fd2065e23b2b85d8e1c78672a66dbe6234437.
However, I don't really like this solution as it adds an extra export
(qof-session-load-0) to engine.i - I couldn't quickly figure out how
to pass scheme functions to qof_session_load..  I've appended some
example code.

There may well be an existing way of doing this as well.

Regards,

Peter

(use-modules (gnucash gnc-module))
(gnc:module-system-init)

(cond-expand
  (guile-2
    (eval-when
      (compile load eval expand)
      (gnc:module-load "gnucash/engine" 0)))
  (else
    (gnc:module-load "gnucash/engine" 0)))

(define (run-test)
  (let* ((session (qof-session-new)))
    (qof-session-begin session "file:///tmp/aaa" #t #f #f)
    (qof-session-load-0 session)
    (gnc-set-current-session session)
    (qof-session-get-book session)))

On 7 November 2015 at 22:21, Alex Weiss <alexweiss at theplate.com> wrote:
> Thanks for your help.  I saw that code.  However, I seem to be missing something.  While the c function qof_session_new is exposed as qof-session-new, the same is not true for qof_session_begin.
>
> In my guile file I include gnucash bindings as so....
>
> (use-modules (gnucash gnc-module))
> (gnc:module-system-init)
> (gnc:module-load "gnucash/engine" 0)
>
> But a call to (qof-session-begin (qof-session-new) "file://agnucashfile.gnucash" #t #f #t)) is considered a call to "Unbound variable: qof-session-begin).
>
> Is qof-session-begin in a different module?
>
> Thanks for your help again,
>
>
>> Sent: Thursday, October 29, 2015 at 12:14 PM
>> From: "John Ralls" <jralls at ceridwen.us>
>> To: "Alex Weiss" <alexweiss at theplate.com>
>> Cc: gnucash-user at gnucash.org
>> Subject: Re: Guile API
>>
>>
>> > On Oct 29, 2015, at 8:04 AM, Alex Weiss <alexweiss at theplate.com> wrote:
>> >
>> > I was considering scripting GnuCash using its Guile API rather that it's Python API?  Am I crazy to assume that the Guile API is as rich an the Python API?
>> >
>> > The first stumbling block I have noticed is simply creating what the Python API calls a "session" - a connection to gnucash will allows for the input and retrieval of GnuCash data. The Python API Session object seems to wraps the c functions: qof_session_new, qof_session_begin, and qof_session_load. The swig interface I found does not seem to export these out as Guile procedures.
>> >
>> > Any advice on using the Guile API in general or how to create a session using Guile in particular?
>>
>> Alex,
>>
>> Actually, more of GnuCash is exposed to Guile than to Python because Python can’t see the parts of GnuCash that are written in Scheme. Everything in the C API that’s exposed to one is exposed to the other; the differences in the SWIG interface files are just customizations needed to make a function work in the language in question. If there’s no customization it means that SWIG can figure out the right thing to do from the C header, and unless a function whose header is included in a SWIG file is specifically %excluded in the SWIG file it’s exported.
>>
>> What’s more, GnuCash links libguile and starts the Scheme interpreter very early, so you can actually customize the application with Scheme. This is how one adds custom reports.
>>
>> That aside, qof_session_new *is* mentioned explicitly in engine.i outside of the language-specific sections, at line 163. You can see it in action in src/engine/test/test-create-account.scm and test-dcm-query-import.scm
>>
>> Regards,
>> John Ralls
>
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