Extension in c, close file when script ends, rb_io_fptr_fina

Ruby
1

hi,
I wrote an extension that uses a file to handle an external device. The
initialize method opens the file and it then is permanently open. I don’
t
want to open and close it every time I write to it.

I wondered how to finalize the object or to close the file when my
script
ends. Currently the file keeps open and I have an open unused device.

I stumbled over the function ‘rb_io_fptr_finalize’, but I didn’ t find a
real reference which tells me if that’ s what I searched for or not.

Can someone help me or give me further infos?

thanks,
Alex.

2

On Thu, Mar 08, 2007 at 04:55:11PM +0900, Alexander F. wrote:

I wrote an extension that uses a file to handle an external device. The
initialize method opens the file and it then is permanently open. I don’ t
want to open and close it every time I write to it.

I wondered how to finalize the object or to close the file when my script
ends. Currently the file keeps open and I have an open unused device.

I’d recommend you copy the way that Ruby’s File class does it.

(1) Provide a ‘close’ method on your object, for the user to be able to
explicitly close it when needed.

(2) Provide a block-based method, which does an open / yield / close
sequence

File.open("/etc/passwd") do |f|
  puts f.read
end
# file is now closed at this point

(preferred implementation is to use begin … ensure … end, so that the
close is called even if an exception occurs when the yield is called)

(3) Let the files close themselves when the program exits.

I stumbled over the function ‘rb_io_fptr_finalize’, but I didn’ t find a
real reference which tells me if that’ s what I searched for or not.

As I understand it, finalisers are called when the object is
garbage-collected. However there’s not guarantee that an object will be
garbage-collected at any time before the program exits (and not even
then,
if the user calls ‘exit!’)

However, if it’s just a file, the operating system will close the file
when
the program exits anyway.

B.