winform的属性设置

[雍和与木]

public static CommandSender Instance
{
get { return device ?? (device = new CommandSender()); }
}

谁能给解释一下这个属性设置是什么意思

[bdmh]

http://www.cnblogs.com/meta/archive/2010/08/11/1797176.html

[exception92]

if（ device  == null）{
   device = new CommandSender();
}

[threenewbee]

return device != null ? device : new CommandSender();

[sunny906]

??

引用 2 楼 duanzi_peng 的回复:

if（ device  == null）{
   device = new CommandSender();
}

+1

引用 3 楼 caozhy 的回复:

return device != null ? device : new CommandSender();

+1 ?? 是 null 合并运算符