有没有更简洁的方法在Ruby中调用外部方法？

Question

有更简洁的方法吗？

# Given a directory containing subdirectories: foo, bar
targets = ['./foo', './bar', './free']
targets.map{ |d| Dir.exists? d }
# => [ true, true, false ]

我希望能够做类似于proc的事情......感觉更干净：

# targets.map( Dir.exists? )

Answer 1

是的，可能这样，但对性能不利（见帖子：Is the &method(:method_name) idiom bad for perfomance in Ruby?）：

targets = ['./foo', './bar', './free']
targets.map(&Dir.method(:exists?))
# => [false, false, false]  #all are false,as I don't have such directories.