On Thu, 09 May 2013 09:07:42 -0400, Roy Smith wrote: > In article <518b32ef$0$11120$c3e8...@news.astraweb.com>, > Steven D'Aprano <steve+comp.lang.pyt...@pearwood.info> wrote: > >> There is no sensible use-case for creating a file without opening it. > > Sure there is. Sometimes just creating the name in the file system is > all you want to do. That's why, for example, the unix "touch" command > exists.
Since I neglected to make it clear above that I was still talking about file objects, rather than files on disk, I take responsibility for this misunderstanding. I thought that since I kept talking about file *objects* and *constructors*, people would understand that I was talking about in-memory objects rather than on-disk files. Mea culpa. So, let me rephrase that sentence, and hopefully clear up any further misunderstandings. There is no sensible use-case for creating a file OBJECT unless it initially wraps an open file pointer. This principle doesn't just apply to OOP languages. The standard C I/O library doesn't support creating a file descriptor unless it is a file descriptor to an open file. open() has the semantics: "It shall create an open file description that refers to a file and a file descriptor that refers to that open file description." http://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html and there is no corresponding function to create a *closed* file description. (Because such a thing would be pointless.) Of course language designers are free to design their language to work under whatever anti-patterns they desire. I quote from the Pascal Language Reference: "open associates the permanent file file [sic] with a file variable for reading or writing. open does not actually open the file; you must call reset or rewrite before reading or writing to that file." http://www.amath.unc.edu/sysadmin/DOC4.0/pascal/lang_ref/ ref_builtin.doc.html but since that's not a part of standard Pascal, other Pascals may behave differently. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
