> Yes it does. What C programmers often do is adding unused vfuncs as
padding for future extension of the class. From this perspective Vala
could theoretically add some kind of padding to avoid abi breakage.
So what about this idea for fix it:
Create a new attribute property in [CCode], named binary_position, that is used
for virtual methods, but can be used for another things(such as fields, etc.).
It can be used by the developer to avoid this risk, by doing so:
Every time the developer create a new virtual method, he shell pick the
smallest number available for virtual method position, and put it in
binary_position in [CCode].
On every planned ABI(&API) break, he can minimize those binary_position(s) for
virtual methods.
This idea is based on the assumption that the size of XClass struct doesn't
matter and can be changed(Am I right?).
Also, how does the virtual method order is currently done by Vala? Is it
alphabetic or by the order of the decelerations?
Thanks
Tal
Date: Sun, 11 Dec 2011 10:48:21 +0100
Subject: Re: [Vala] Can adding new virtual method break ABI?
From: lethalma...@gmail.com
To: tal...@hotmail.com
CC: vala-list@gnome.org
2011/12/11 Tal Hadad <tal...@hotmail.com>
I've read how GObject define virtual methods, in the XClass struct, and
I'm afraid defining new virtual method can break ABI. Am I right?
Before:
struct _XClass
{
GObjectClass parent_class;
/* stuff */
void (*do_action) (X *self, /* parameters */);
};
After:
struct _XClass
{
GObjectClass parent_class;
/* stuff */
void (*another_action) (X *self, /* parameters */);
void (*do_action) (X *self, /* parameters */);
};
Can this case break ABI?
Yes it does. What C programmers often do is adding unused vfuncs as padding
for future extension of the class. From this perspective Vala could
theoretically add some kind of padding to avoid abi breakage.
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