Pádraig Brady wrote:
> I'd especially like a review of the perl bits
Hi Pádraig,
I'm not sure that this function will behave quite as you intended it to:
+sub getlimits()
+{
+ my $NV;
+ open NV, "getlimits |" or die "Error running getlimits\n";
+ my %limits = map {split /=|\n/} <NV>;
+ return \%limits;
+}
+
I think that filehandle is opened using a broader scope than you might
be expecting. It's not using your subroutine-scoped lexical $NV, but
rather a package-scoped "NV" symbol. If you open $NV and read using
<$NV> it will use your subroutine-scoped lexical variable, as I think
you intended.
Please see the attached demonstration of this:
$ ./filehandles.pl
limits: 'foo'
caller: ''
$ ./filehandles.pl safe
limits: 'foo'
caller: 'bar'
Thanks,
Bo
#!/usr/bin/perl
my ($safe) = @ARGV;
system ("echo -n foo > test_foo");
system ("echo -n bar > test_bar");
sub getlimits {
my $NV;
# This clobbers caller's "NV"
open NV, "<", "test_foo" or die "Failed to open test_foo: $!";
<NV>;
}
sub getlimits_safe {
my $NV;
# This uses subroutine-scoped "$NV"
open $NV, "<", "test_foo" or die "Failed to open test_foo: $!";
<$NV>;
}
open NV, "<", "test_bar" or die "Failed to open test_bar: $!";
my $limits = $safe ? getlimits_safe : getlimits;
my $caller = <NV>;
print "limits: '$limits'\n";
print "caller: '$caller'\n";
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