[GRASS-dev] [bug #5483] (grass) g.mremove through gis manager GUI seems not to work well

[Hamish]

Maciej:
> > What do you think about this: if g.mremove cannot remain
> > half-interactive, I'd suggest getting rid of it alltogether, and
> > replacing it's manual page with an instruction how to use "g.mlist
> > sep=," and feed it's output to g.remove by hand (I can write it).

No, just remove it from the GUI if the possibility of interactivity is
an issue, or create a wrapper script for the GUI which does not include
the offending flag. I don't think it is so bad to have command-line-only
power-tools, and to leave g.mremove out of the GUI if that's what is
required.

> > Although removing a module during GRASS 6 should be avoided too, I
> > think that this would do less harm than letting g.mremove delete
> > user's data without control.

Removing a module during GRASS 6 should not be allowed at all.
That will break scripts and render documentation+books out of date.

> > Or maybe revert the changes in g.mremove as it was, for GRASS 6, and
> > postpone working on it to GRASS 7? As for GRASS 7, I'd still vote on
> > removing it completely, as described above, instead of removing it's
> > interactiveness, for the sake of user's data.

Glynn:
> Alternative possibilities:
> 
> 1. Rename g.mremove (e.g. to g.remove.multi); if anyone asks where it
> went, remind them that the new version doesn't request confirmation.
> 
> 2. Revert g.mremove, add a version which doesn't prompt, change gis.m
> to only refer to the non-prompting version.
> 
> Personally, I'd favour #1; option #2 undermines attempts to get
> developers to realise that terminal interaction is unacceptable.

Personally I'd prefer #2 or removing g.mremove from the GUI menu vs.
adding yet another duplicate module.

but wait --

** A compromise idea: make g.mremove without "-f" exit (0 or 1?) after
listing the files the regex would match; have it only delete something
if "-f" is used. The extra tick of brain activity to type the extra 3
chars should be enough to invoke the do-I-really-want-to-do-this 2nd
thought, if not, well that's not our problem, we tried. That way we only
"break" interactive mode, and the new solution is in a way interactive
(they have to retype the command).

 -- patch attached.

> In my experience, any rule with an "except in special cases" qualifier
> may as well not exist. Everyone thinks that their pet case qualifies,
> and you end up with a useless mess.
>
> Either you can rely upon GRASS commands being scriptable, or you
> can't. Right now, you can't;

Point taken.

> if you try to build something on top of GRASS, sooner or later
> something is going to try to prompt the non-existent user for input
> which will never arrive.

It's a worthy goal, and something we should do for GRASS 7, but we can't
go around breaking people's scripts in order to make their scripts
easier to write! [Glynn's patch in CVS does not do that; some of the
proposed solutions might] As far as g.mremove goes, I imagine scripters
figured out they needed to use "-f" when they wrote it.


So how do folks feel about the compromise solution? Without -f it skips
the y/n prompt, forcing "no", and a functional g.remove command line is
sent to stdout for perusal[, piping, logging, whatever], along with a
message to stderr that you need to use -f if you actually want to remove
files.


Hamish
-------------- next part --------------
Index: scripts/g.mremove/g.mremove
===================================================================
RCS file: /home/grass/grassrepository/grass6/scripts/g.mremove/g.mremove,v
retrieving revision 1.11
diff -u -r1.11 g.mremove
--- scripts/g.mremove/g.mremove	7 Feb 2007 14:58:49 -0000	1.11
+++ scripts/g.mremove/g.mremove	12 Feb 2007 09:09:05 -0000
@@ -28,7 +28,7 @@
 
 #%flag
 #%  key: f
-#%  description: ignored (retained for compatibility with previous versions)
+#%  description: force removal (required for actual deletion of files)
 #%end
 
 #%option
@@ -205,5 +205,14 @@
 	echo "No data found."
 	exit 1
 fi
+
+if [ $force -eq 0 ] ; then
+    echo "The following files would be deleted:" 1>&2
+    echo "g.remove $rast $rast3d $vect $icon $labels $region $group $dview"
+    echo 1>&2
+    echo "You must use the force flag to actually remove them. Exiting." 1>&2
+    exit 0
+fi
+
 
 exec g.remove $rast $rast3d $vect $icon $labels $region $group $dview