Re: Status of callback interface enhancements

On Thursday 26 February 2004 08:30, Kevin Tambascio wrote:
> Hi,
>
> I am a developer with KMyMoney, and we are looking at using libofx as part
> of our software, so that we can import ofx files.
>
> I started to write our implementation, but ran into a few issues.  First
> off, there is no way to register callbacks, in our case, static C++ member
> functions.  I don't see how they would be called with the current library.

Currently they are linked at compile time.  It's a design mistake I made early 
on (inspired by OpenSP's interface), but it is fairly simple to use.  See 
ofxdump.cpp  If the flow is currently disruptive to your object model (such 
as if you can't garantee that you have a necessarly object created to receive 
the call, just wrap the code in another object whose sole job is to remember 
whatever info you need to pass data to the rest of your app.

> The second issue, was that when the callbacks would be called, I do not
> have access to my class's instance.  I know with expat, the callback
> functions send you a void* that you can set in the beginning to associate
> with your class's instance.

This is partially implemented in CVS by Ryan P Bobko.  Not complete thought.

> If this is not possible/desired, have you considered a DOM-style interface,
> where the document is parsed, and client's can then walk the tree?  This
> would avoid the problem of having to have a callback mechanism.

Yes, the next major version of LibOFX will have this, and in fact will be the 
only way to access the data elements (except for things ike status which 
obviously need a callback.  It's already done internally, I just need to 
write the API to access it. But as it's a source incompatible change it won't 
be released early.  We need this to allow out of order access to data (such 
as creating all accounts before we process transactions) and to allow 
bidirectionnal communication.

> It looks like some of this has been covered in your mailing list, but I
> didn't see anything about what the final plan will be.  I'm currently
> trying out 0.6.6.

The plan is:
-The API for LibOfx 0.6.x won't change, and will likely remain the released 
version for months to come
-The next major release will have registerable callbacks with void * user 
data, and well as a walkable tree for the different elements.  API not done 
yet.

Feel free to ask for any more details, or catch me on #gnucash on 
irc.gnome.org.   I can also take a look at your code if it's in a CVS 
somewhere.

-- 
Benoit Grégoire, http://step.polymtl.ca/~bock/


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