如何设置GetOpt的默认值？

Question

我认为它是那么容易，因为：

my $man = 0; 
my $help = 0; 
my @compList = ('abc', 'xyz'); 
my @actionList = ('clean', 'build'); 

## Parse options and print usage if there is a syntax error, 
## or if usage was explicitly requested. 
GetOptions('help|?' => \$help, man => \$man, 'complist:s@' => \@compList, 'action:s@' => \@actionList) or pod2usage(2); 

然而，当我这样做：

script.pl --action clean 

而且打印我actionList，它只是追加我的参数来结尾：clean build clean

Answer 1

对于标量，在调用GetOptions时设置默认值。但是，对于数组，您需要更明确地使用逻辑。

## Parse options and print usage if there is a syntax error, 
## or if usage was explicitly requested. 
GetOptions(
    'help|?'  => \(my $help = 0), 
    'man'   => \(my $man = 0), 
    'complist:s@' => \my @compList, 
    'action:s@' => \my @actionList, 
) or pod2usage(2); 

# Defaults for array 
@compList = qw(abc xyz) if !@compList; 
@actionList = qw(clean build) if !@actionList; 

注意，因为$help和$man只是布尔标志，它实际上不是必要的初始化。依靠它们的默认值undef可以正常工作，除非您尝试在某处打印其值。

Answer 2

可以GetOptions后的默认设置，如下所示：

my @compList; 
GetOptions('complist:s@' => \@compList) or pod2usage(2); 
@compList = qw(abc xyz) unless @compList;