RE: [Brlcad-users] Mk_* and Friends

[Browder, T. <Tom...@fw...>]

Thanks, Sean, that's very helpful--just what the doctor ordered.

-Tom=20

> -----Original Message-----
> From: Christopher Sean Morrison [mailto:br...@ma...]=20
> Sent: Wednesday, August 31, 2005 11:42 AM
> To: Browder, Tom
> Cc: Brl...@li...;=20
> 'brl...@li...'
> Subject: Re: [Brlcad-users] Mk_* and Friends
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> Tom,
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> I'd consider that artifact that it leave an object a bug=20
> myself.  If an mk_ function fails, the database should not be=20
> modified.  That said, as you noted it does now so you need=20
> some sort of failure recovery. =20
> Libwdb doesn't handle that functionality directly, librt=20
> does.  For what it's worth, libwdb is actually spawned off of=20
> librt so there is a lot of cross-over between the two and as=20
> soon as you cross the line of doing anything more than simply=20
> writing out geometry, librt takes over.
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> So, the routine you need from librt that you can call is the=20
> same command that mged ultimately uses for the kill command: =20
> db_delete(). =20
> The command is defined in src/librt/db_alloc.c as follows:
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> int db_delete(struct db_i *dbip, struct directory *dp);
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> That db_i pointer is actually stashed inside the struct=20
> rt_wdb * that you opened, and all you need to acquire is a=20
> handle on the object in the database directory.  This is done=20
> via db_lookup().  Since you probably also then want to remove=20
> the object from the in-memory directory, a call to=20
> db_dirdelete() is also in order.  To put it all together into=20
> an example snippet:
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> struct rt_wdb *fp =3D wdb_fopen("blah.g"); struct directory *dp=20
> =3D db_lookup(fp->dbip,  "blah.r", 0);
> /* third argument to db_lookup is a verbose flag */
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> if (dp) {
>    bu_log("couldn't find object blah.r\n"); }
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> if (db_delete(fp->dbip, dp) || db_dirdelete(fp->dbip, dp)) {
>    bu_log("delete failed\n");
> } else {
>    bu_log("delete succeeded\n");
> }
> wdb_close(fp);
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> These is definitely a thread more suited to the brlcad-devel=20
> mailing list instead of the brlcad-users list.. ;-)
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> Cheers!
> Sean
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> On Aug 30, 2005, at 4:40 PM, Browder, Tom wrote:
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> > When using libwdb in a C program and a mk_* function fails,=20
> the name=20
> > of the object remains in the db.  How does one remove it using C=20
> > functions?
> >
> > Thanks.
> >
> > Tom Browder
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>=20