ruby - 如何在ruby中获取文件模式？

Question

我是 ruby​​ 文件 IO 的新手。我有一个带有 File 参数的函数，我需要确保该文件处于只读模式。

def myfunction(file)
    raise ArgumentError.new() unless file.kind_of?(File)

    #Assert that file is in read-only mode
end

如有任何帮助，我们将不胜感激!

Answer 1

如果你不需要报错，你可以使用reopen，我想是这样的:

file = file.reopen(file.path, "r")

我找不到其他方法来验证不存在写入流，但这里有一些可行的技巧。虽然我不喜欢在预期路径中使用异常抛出，但您可以使用 close_write:

begin
  file.close_write
  # you could actually raise an exception here if you want
  # since getting here means the file was originally opened for writing
rescue IOError
  # This error will be raised if the file was not opened for
  # writing, so this is actually the path we want
end