File::Find::Rule::LibMagic: Is it ok to keep options with undefined values?
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22-04-2021 - |
문제
Is it OK to keep options with undefined values (in this case 'maxdepth')?
#!/usr/bin/env perl
use warnings;
use 5.012;
use File::Find::Rule::LibMagic qw(find);
use Getopt::Long qw(GetOptions);
my $max_depth;
GetOptions ( 'max-depth=i' => \$max_depth );
my $dir = shift;
my @dbs = find( file => magic => 'SQLite*', maxdepth => $max_depth, in => $dir );
say for @dbs;
Or should I write it like this:
if ( defined $max_depth ) {
@dbs = find( file => magic => 'SQLite*', maxdepth => $max_depth, in => $dir );
} else {
@dbs = find( file => magic => 'SQLite*', in => $dir );
}
해결책
There should be no problem in having maxdepth
set to undef
by using a variable with undef
as its value. Every variable in Perl starts out with the undef
value.
More Details
File::Find::Rule::LibMagic
extends File::Find::Rule
. The find
function in File::Find::Rule
starts with:
sub find {
my $object = __PACKAGE__->new();
The new
functions returns:
bless {
rules => [],
subs => {},
iterator => [],
extras => {},
maxdepth => undef,
mindepth => undef,
}, $class;
Note that maxdepth
by default is set to undef
.
다른 팁
OK? It probably won't confuse File::Find::Rule
$ perl -MFile::Find::Rule -le " print for File::Find::Rule->maxdepth(undef)->in( q/tope/ ) "
tope
tope/a
tope/b
tope/c
tope/c/0
tope/c/1
tope/c/2
$ perl -MFile::Find::Rule -le " print for File::Find::Rule->maxdepth(1)->in( q/tope/ ) "
tope
tope/a
tope/b
tope/c
$ perl -MFile::Find::Rule -le " print for File::Find::Rule->maxdepth(-1)->in( q/tope/ ) "
tope
$ perl -MFile::Find::Rule -le " print for File::Find::Rule->maxdepth(2)->in( q/tope/ ) "
tope
tope/a
tope/b
tope/c
tope/c/0
tope/c/1
tope/c/2
$ pmvers File::Find::Rule
0.33
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