perl - 如何设置GetOpt的默认值？

Question

我认为这很简单:

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);

但是，当我这样做时:

script.pl --action clean

然后我打印我的 actionList，它只是将我的参数附加到末尾:clean build clean

Answer 1

对于标量，在 GetOptions 调用中设置默认值。但是，对于数组，您需要更明确地表达您的逻辑。

## 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;

请注意，由于 $help 和 $man 只是 bool 标志，因此实际上没有必要初始化它们。除非您尝试在某处打印它们的值，否则依赖它们的默认 undef 效果很好。