# Method Stdio.Buffer()->output_to()

Method output_to

  `int(-1..) output_to(Stdio.Stream|function(string:int) fun, int(0..)|void nbytes)`

Description

  Write data from the buffer to the indicated file.

Parameter `fun`

  Write function. Either one of:

  `Stdio.Stream` | A file object in which the function `write()` will be called.
  `function(string:int)` | A function which will be called with a `string(8bit)` to write and is expected to return an `int` indicating the number of bytes successfully written or `-1` on failure.

Parameter `nbytes`

  If nbytes is not specified the whole buffer will be written if possible. Otherwise at most nbytes will be written.

Returns

  Will return the number of bytes that have been written successfully.

  If no bytes have been written successfully and `fun()` failed with an error, `-1` will be returned.