Mike Martin wrote:
> Hi
>
> I was always under the impression that a foreach loop iterated over a
> list sequentially, which in every other case at least seems to happen.
>
> However I have the following code
foreach file
run command on file
> Which runs the following sub-routine (abrev) for each file ($files above)
>
> sub run_cmd {
> $pid=open($file, "-|","$cmd{$subname} 2>&1") or die "Failed running
> perl subprocess\n";
This forks a child that runs concurrently....
[snip text buffer setup]
> our $tag= Glib::IO->add_watch ( fileno($file), ['in', 'hup'], sub {
[snip]
}
);
This installs a callback to be run by the main loop when data arrives on the
file handle connected to the child's output, or when that file hangs up.
> }
And then you return.
Which means that all run_cmd() actually does is fork the child and set up the
main loop to listen to it. It does not wait, irrespective of what the
callback does.
> However the sub is run for each file in parallel. Anyone have any idea
> how to force sequential mode?
You need to keep the UI responsive while this is happening, so you must run a
main loop. You can run a main loop at the end of run_cmd() to keep the
control flow stopped there until either the child completes and kills the main
loop, or a cancel button causes you to kill the child and quit that nested
main loop. E.g.:
sub run_cmd {
my $file = open_child_process (...);
Glib::IO->add_watch (fileno ($file), ['in', 'hup'], sub {
my (undef, $cond) = @_;
if (user_wants_to_cancel ()) {
kill_child ();
# let this proceed naturally; we'll get another
# call with HUP next time around.
}
if ($cond >= 'in') {
handle_the_input_data ();
}
if ($cond >= 'hup') {
close ($file);
# Kill the nested main loop, see below
Gtk2->main_quit ();
return FALSE;
}
return TRUE;
});
# Now wait here for the IO watch to kill this nested main loop.
Gtk2->main ();
}
--
muppet <scott at asofyet dot org>
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