Re: [PATCH v2 28/43] refs.c: add ref backend init function

> On 09/29/2015 12:02 AM, David Turner wrote:
> > The file backend doesn't need this function, but other backends might.
> > 
> > Signed-off-by: David Turner <dturner@twopensource.com>
> > Signed-off-by: Ronnie Sahlberg <rsahlberg@google.com>
> > ---
> >  refs-be-files.c | 1 +
> >  refs.c          | 4 +++-
> >  refs.h          | 4 +++-
> >  3 files changed, 7 insertions(+), 2 deletions(-)
> > 
> > diff --git a/refs-be-files.c b/refs-be-files.c
> > index 37e244a..eaa74b6 100644
> > --- a/refs-be-files.c
> > +++ b/refs-be-files.c
> > @@ -3737,6 +3737,7 @@ int reflog_expire(const char *refname, const unsigned char *sha1,
> >  struct ref_be refs_be_files = {
> >  	NULL,
> >  	"files",
> > +	NULL,
> >  	files_transaction_begin,
> >  	files_transaction_update,
> >  	files_transaction_create,
> > diff --git a/refs.c b/refs.c
> > index 769574d..9ce10b7 100644
> > --- a/refs.c
> > +++ b/refs.c
> > @@ -19,13 +19,15 @@ struct ref_be *refs_backends = &refs_be_files;
> >  /*
> >   * This function is used to switch to an alternate backend.
> >   */
> > -int set_refs_backend(const char *name)
> > +int set_refs_backend(const char *name, void *init_data)
> >  {
> >  	struct ref_be *be;
> >  
> >  	for (be = refs_backends; be; be = be->next)
> >  		if (!strcmp(be->name, name)) {
> >  			the_refs_backend = be;
> > +			if (be->init_backend)
> > +				be->init_backend(init_data);
> 
> I don't like that this virtual function, alone among all of them
> introduced so far, is allowed to be NULL. That seems non-obvious and
> something extra that devs have to remember.
> 
> I think it would be better for the files backend to define a do-nothing
> function that can be stuck in this slot.