[Geany-devel] geany-plugins depends on GIO - plugin API version checks

[Nick Treleaven]

On Fri, 26 Nov 2010 07:06:12 +1100
Lex Trotman <elextr at gmail.com> wrote:

> On 26 November 2010 04:07, Nick Treleaven <nick.treleaven at btinternet.com> wrote:
> > On Thu, 25 Nov 2010 10:54:07 +1100
> > Lex Trotman <elextr at gmail.com> wrote:
> >
> >> On 24 November 2010 23:54, Nick Treleaven <nick.treleaven at btinternet.com> wrote:
> >> > On Tue, 23 Nov 2010 09:09:59 +1100
> >> > Lex Trotman <elextr at gmail.com> wrote:
> >> >
> >> >> But the general consensus seems to be that people are happy to use
> >> >> static versioning and to keep conpiling (well it is the developer
> >> >> list) and either manually checking what has changed in an API/ABI
> >> >> break or (more probably) to hope that C's leaky type system catches
> >> >> any problem.
> >> >
> >> > ABI checking is automatic, not manual (assuming the
> >> > PLUGIN_VERSION_CHECK() macro is used and not manually implemented
> >> > wrongly).
> >>
> >> What I meant was that if the version fails, my guess is that most
> >> plugin devs just bump the version in their plugin and recompile and
> >> hope that the compiler catches any incompatible changes.  Only the
> >> really conscientious ones will check which functions changed and if it
> >> affects their code.
> >
> > No, plugins should not have any ABI number constant in their source.
> > See the source for PLUGIN_VERSION_CHECK().
> 
> That checks that the version of geany loading the plugin matches the
> version the plugin was compiled with.  It doesn't check that the
> recompiled plugin works with the new ABI which is what I'm talking
> about.  Only the compiler (if you are lucky) or manual checks can do
> that.

When we break the ABI we try to do it so the compiler would catch any
problems - usually we would remove the old field name or function name.

(Plugin devs don't need to bump anything when the ABI changes.)

> >> Don't you use:
> >>
> >> #if GEANY_ABI_VERSION != xxx /* or whatever conditions */
> >> #error ABI mismatch
> >> #endif
> >>
> >> for compile time check??
> >
> > There is no need to try to do that if plugins use the
> > PLUGIN_VERSION_CHECK macro (which all should), and xxx would need to be
> > read from Geany anyway, so that can't be done with the preprocessor.
> 
> 1. PLUGIN_VERSION_CHECK is a runtime check, this is a compile time check
> 
> 2. GEANY_ABI_VERSION and GEANY_API_VERSION *are* read from Geany, they
> are in plugindata.h and as noted above there isn't a runtime way of
> reading them.  The xxx is the version the plugin uses and has to be a
> constant in the source.
> 
> 3. GEANY_VERSION_CHECK requires GEANY_ABI_VERSION match what it was
> compiled with, it can't check that its a version the plugin can use or
> refuse to compile if it isn't.

I think it's too complicated to have a plugin compatible with 2 or more
ABIs. It's asking for trouble.

Nick