[GRASS-dev] g.list -a

[Martin Landa]

Hi,

I have just one general (maybe a little bit silly;-) question. There
are number of modules which follow this pattern:

* there is one (determinative) parameter (e.g. type in g.list)
* and the flag for all types (e.g. -a -- List all data types)

I can see two distinct approaches:

1) the determinative parameter is requested

-> usage: g.list -a type=

This is more precise for parsing syntax of the module, I think. On the
other hand a little bit confusing for the user.

2) the determinative parameter is not requested

-> usage: g.list -a

This construction is more clear for the user I hope. But it cause more
problems for programmer -- there is a need to handle meaningless usage
of the module, e.g. g.list -f (verbose listing).

I am not sure which approach is better.

Best regards, Martin

2006/12/27, Martin Landa <landa.martin at gmail.com>:
> Hi,
>
> 2006/12/27, Glynn Clements <glynn at gclements.plus.com>:
> >
> > Martin Landa wrote:
> >
> > > > > I am trying to implement the wish [1]. I found a strange construction
> > > > > in g.list module. The -f flag (full listing) calls the external
> > > > > program $GISBASE/etc/lister/[cell|vector]. These little programs are
> > > > > called only in g.list -f (I think).
> > > > >
> > > > > I rewrote g.list without calling any external program -- i.e. I moved
> > > > > functions from lister directory to lib/lister.c. If there are no
> > > > > serious objections I will commit it to CVS.
> > > >
> > > > Don't remove the existing functionality; add a new switch for using
> > > > your built-in lister.
> > >
> > > this patch does not remove any functionality (AFAIK). The only change
> > > is: the functionality of lister (programs) is moved to lib/lister.c. I
> > > don't see any reason why to have this functionality (the -f flag)
> > > outside of the g.list (/etc/lister/[cell|vector]). Maybe there is a
> > > particular reason for this construction, please let me know. Thanks!
> >
>
> > The user can install lister programs for other types and/or replace
> > existing ones.
>
> OK, it makes sense to me (only it's hard to imagine an user how
> installs other lister program instead of changing the code;-)
>
> > The point of -f isn't so much to provide specific additional
> > functionality, but to allow the handling to be deferred to an external
> > program.
>
> You are right, I have tried to change the patch in this way, not sure
> if I am working with child process as I should have. In any case
> g.list works:-)
>
> Martin
>
> > --
> > Glynn Clements <glynn at gclements.plus.com>
> >
>
>
> --
> Martin Landa <landa.martin at gmail.com> * http://gama.fsv.cvut.cz/~landa *
>
>
>


-- 
Martin Landa <landa.martin at gmail.com> * http://gama.fsv.cvut.cz/~landa *