Re: [Libguestfs] [PATCH] Export inspect_linux_kernel in Lib.pm
Matthew Booth wrote:
diff --git a/perl/lib/Sys/Guestfs/Lib.pm
b/perl/lib/Sys/Guestfs/Lib.pm
...
@@ -1551,10 +1552,19 @@ sub _check_for_kernels
...
# Check the kernel was recognised
if(defined($kernel)) {
+ # Put this kernel on the top level kernel list
+ my $kernels = $os->{kernels};
+ if(!defined($kernels)) {
+ $kernels = [];
+ $os->{kernels} = $kernels;
+ }
+ push(@$kernels, $kernel);
+
Hi Matt,
It took me too long to see what was being done above,
so I rewrote it in a way that I found easier to read:
How about this?
diff --git a/perl/lib/Sys/Guestfs/Lib.pm b/perl/lib/Sys/Guestfs/Lib.pm
index dfa79af..2acdec6 100644
--- a/perl/lib/Sys/Guestfs/Lib.pm
+++ b/perl/lib/Sys/Guestfs/Lib.pm
@@ -1558,12 +1558,8 @@ sub _check_for_kernels
# Check the kernel was recognised
if(defined($kernel)) {
# Put this kernel on the top level kernel list
- my $kernels = $os->{kernels};
- if(!defined($kernels)) {
- $kernels = [];
- $os->{kernels} = $kernels;
- }
- push(@$kernels, $kernel);
+ $os->{kernels} ||= [];
+ push(@{$os->{kernels}}, $kernel);
$config{kernel} = $kernel;
The ||= operator may look odd, but it's another of these idiom things.
Once you see it a few times, then "get it", and start using it,
you'll never go back.
Which would you prefer to read/maintain? This:
# Ensure the array-ref is initialized.
if (!defined $some_long_name->[$some_complicated_expression]) {
$some_long_name->[$some_complicated_expression] = [];
}
# Append to it.
...
or this:
# Ensure the array-ref is initialized.
$some_long_name->[$some_complicated_expression] ||= [];
# Append to it.
...