I want something like..
my $sub = $ARGV[1];
...
@objs = get_all_objects();
for my $obj (@objs) {
// invoke subroutine $sub with param as $obj.
}
now if I say
all_objects.pl "print 'x '"
all_objects.pl "print '$_ '"
I should get
obj1 obj2 obj3 ...
i.e. the command line arg act as a subroutine in some way. Can this be achieved?
eval "" is bad. Use something like the following, if it fulfills your needs:
my ($sub) = @ARGV;
my %prepared = (
print => sub { print "$_[0]\n" },
woof => sub { $_[0]->woof },
meow => sub { $_[0]->meow },
);
@objs = get_all_objects();
for my $obj (@objs) {
$prepared{$sub}->($obj);
}
Update: For debugging purposes, Perl has a debugger: perldoc perldebug
Eval is evil unless you really know what you're doing (think of it as an unshielded thermonuclear nuke -- sure you could handle one if you had to, and it might even save the world, but you'd be better off leaving it as a last resort, and let the nuclear physicists deal with it.)
You could put your all_objects.pl code into a module, and then use the module on the command line:
put this into AllObjects.pm:
package AllObjects;
use strict;
use warnings;
sub get_all_objects
{
# code here...
}
1;
Now on the command line:
perl -I. -MAllObjects -wle'for my $obj (AllObjects::get_all_objects()) { print "object is $obj" }'
However, it's not really clear what you are trying to achieve with the overall design.
You can read more about perl command-line invokation at perldoc perlrun, and making modules at perldoc perlmod (as well as many posts here on Stack Overflow).
eval may be an unshielded nuke, but block eval is just Perl's way of spelling try. Not all evals are evil. (But OP was looking for string eval, so carry on...)