Martin Landa wrote:
there are couple of functions which allow passing fully qualified map
name even they have mapset argument available.
E.g.
G__open() where you can pass name as fully qualified, then 'mapset'
argument is ignored.
If you pass a fully-qualfied name, it fails if the mapset part of the
name doesn't match the mapset argument. It should probably accept ""
as the mapset to skip this check, as for G_find_*.
Most functions which reference an existing map (or other element)
accept both a name and a mapset.
If the mapset is non-empty, unqualified names use that mapset while
qualified names must have an @mapset part which matches it.
If the mapset is the empty string (""), qualified names use their
@mapset part while unqualified names use the mapset search path (the
default is the current mapset followed by PERMANENT).
Functions which create a new map or other element only work with the
current mapset and don't accept a mapset argument. Unqualified names
refer to the current mapset, while qualified names must have the
current mapset as their @mapset part.
Maybe this behaviour could be changed in GRASS 7,
either to require not-fully qualified names or just to omit 'mapset'
argument and expect that name is fully qualified? First choice seems
to be more reasonable.
I really want to eliminate mapsets altogether from the higher-level
functions. Modules should be able to pass opt->answer directly to most
GRASS functions without needing to call G_find_* or know anything
about mapsets.
Currently functions G_find_cell / G_find_cell2 return mapset name or
NULL. Maybe we could eliminate G_find_*2 function by adding a new
argument.
G_find_cell(fname, mapset, name)
where name is char * to not-fully qualified name (allocated by G_store())
or just
G_find_cell(fname, mapset, NULL) (as G_find_cell2)
Ideally, modules shouldn't need to use the G_find_* functions. In most
cases, use of G_find_* has been unnecessary since the libgis functions
were modified to accept fully qualified names, rather than requiring
the caller to "de-qualify" the name beforehand.
It should normally be sufficient to just use e.g.:
G_open_cell_old(input->answer, "")
rather than e.g.:
mapset = G_find_cell2(input->answer, "");
G_open_cell_old(input->answer, mapset);
[error checking elided.]
If all of the unnecessary G_find_* calls are eliminated, most of the
mapset arguments will eventually become "", at which point the
parameter can be eliminated altogether. If you need to force a
specific mapset, you can construct a qualified name with
G_fully_qualified_name().
But first, we should track down and replace any residual uses of
G_find_cell() (which overwrites the name argument with the unqualified
version). If you really need to de-qualify a name (e.g. because you're
using it as a base for generting map names[1]), use an explicit call
to G__name_is_fully_qualified().
--
Glynn Clements <glynn@gclements.plus.com>