class type file_descr = object .. end
Abstraction of an object providing a file descriptor. The file_descr
method is invoked to get a new descriptor after the old one has been
disposed.
method file_descr : Unix.file_descr
Get the file descriptor or raise an exception if this is not possible.
This method is called when the descriptor is needed but unknown.
file_descr is only allowed to return a different descriptor
than before when dispose_hint has been called in the meantime.
method dispose_hint : unit -> unit
Called by higher layers to notify this object that it is now allowed
to close the Unix descriptor, and that the next call of file_descr
is permitted to return a different descriptor.