[ruby-core:67451] Re: [ruby-trunk - Feature #10718] [Open] IO#close should not raise IOError on closed IO objects.

I think the API is improved but I'm not sure we need to find & replace
every occurrence in the stdlib

On Thursday, January 8, 2015, <[e-mail]> wrote:

> Issue #10718 has been updated by Eric Wong.
>
>
>  Thank you for proposing this.  I think this will simplify working with
>  Ruby IO and make me happier since I work with a lot of IO-related code.
>  Outside of test cases, I don't forsee compatibility problems either.
>
> ----------------------------------------
> Feature #10718: IO#close should not raise IOError on closed IO objects.
> https://bugs.ruby-lang.org/issues/10718#change-50875
>
> * Author: Akira Tanaka
> * Status: Open
> * Priority: Normal
> * Assignee:
> * Category:
> * Target version:
> ----------------------------------------
> I'd like to change IO#close.
> It should not raise IOError on closed IO objects.
>
> We sometimes invoke IO#close only when the IO object is not closed as:
>
> ```
> f.close if !f.closed?
> ```
>
> If this issue is accepted, we can write it simply as follows.
>
> ```
> f.close
> ```
>
> Simple grep finds many examples.
> Following examples are just a little excerpt.
>
> ```
> lib/webrick/server.rb:          sock.close unless sock.closed?
> lib/pstore.rb:          file.close if !file.closed?
> lib/mkmf.rb:          @log.close if @log and not @log.closed?
> lib/cgi/session.rb:          f.close if f and !f.closed?
> lib/open-uri.rb:          io.close if !io.closed?
> lib/net/pop.rb:        s.close if s and not s.closed?
> lib/net/http.rb:          @socket.close if @socket and not @socket.closed?
> lib/net/smtp.rb:        s.close if s and not s.closed?
> lib/shell/process-controller.rb:                io.close unless io.closed?
> test/ruby/test_io.rb:    w.close unless !w || w.closed?
> ...
> ```
>
> I think there is no problem with the behavior which IO#close doesn't raise
> an exception on closed IO object.
> Because the closed state fulfils the postcondition of the method.
>
> Moreover raising IOError can smash other exceptions if it is called in
> ensure clause.
> It makes debugging difficult and the proposed behavior ease it.
>
> It also useful to close IO object asynchronously.
> Asynchronous close can be used for graceful shutdown.
> This issue can eliminate "rescue IOError".
> See lib/webrick/server.rb and lib/drb/drb.rb for example.
>
> Note that "double close" is a bad idea in C.
> But it is not applicable to Ruby.
> A FILE structure is freed on fclose().
> But Ruby's IO object is not freed until GC.
> So method invocation on closed object doesn't cause invalid memory access.
> A file descriptor (FD) can be reused any time because a signal handler or
> another thread may allocate a FD.
> But Ruby's IO object is not reused after close.
> So it is impossible to close an IO object unintentionally.
>
>
> ---Files--------------------------------
> io-close.patch (1.97 KB)
>
>
> --
> https://bugs.ruby-lang.org/
>