Hi,
I'm trying to find a good way for CAD::Drawing::IO to determine which of the
CAD::Drawing::IO::* modules are available.
Basically, there are save() and load() functions in IO.pm which allow an
explicit "type" argument or the type can be derived from the file extension.
Right now, the beginning of IO.pm is just like:
use CAD::Drawing::IO::OpenDWG;
use CAD::Drawing::IO::PostScript;
use CAD::Drawing::IO::Image;
use CAD::Drawing::IO::PgDB;
use CAD::Drawing::IO::Circ;
use CAD::Drawing::IO::Tk;
our @ISA = qw(
CAD::Drawing::IO::OpenDWG
CAD::Drawing::IO::PostScript
CAD::Drawing::IO::Image
CAD::Drawing::IO::PgDB
CAD::Drawing::IO::Circ
CAD::Drawing::IO::Tk
);
The main reason that I'd like to be able to make each module optional is that
OpenDWG.pm requires DWGI.pm (a wrapper on a non-gpl toolkit which I cannot
distribute with the module.)
>From looking at DBI.pm, available drivers are found by searching @INC when
connect() is called, and then there is a require(). I don't think that I
need anything as elaborate as the DBI setup, and I'd rather that this just be
done at compile time (plus, searching @INC seems like a waste and IO.pm needs
to know which save_<type>() and load_<type>() functions are available in
order to redirect to the backend.)
Since adding a backend requires changes to IO.pm, maybe it should just be part
of the IO.pm install procedure? Or, I could look at entirely removing the
type determination and redirects from IO.pm (allowing the backends to
"install" themselves (and then looping through the list of available
backends, calling an is_this_yours() function to allow the implicit filetype
determination to come from the backend itself?)), but I'm not sure how to go
about that.
Currently, the redirection is like so:
# (stripped from the middle of a longer function in IO.pm)
elsif($type eq "postscript") {
($action eq "save") && return($self->saveps($filename, $opt));
($action eq "load") && return($self->loadps($filename, $opt));
}
elsif($type eq "image") {
($action eq "save") && return($self->saveimg($filename, $opt) );
($action eq "load") && return($self->loadimg($filename, $opt) );
}
Thanks in advance for any suggestions,
Eric
