> > >> > > >> Maybe some of these things could be simpler if it was clarified that a > > >> context manager shouldn't acquire resource before __enter__ and a new > > >> version of open was provided. > > >> > > > > > > Hmm. What exactly is the object that you have prior to the file being > > > opened? It can't simply be a File, because you need to specify > > > parameters to the open() call. Is it a "file ready to be opened"? > > > What's the identity of that? > > > > The notion of a “file ready to be opened” makes some sense. I’d expect > such a thing to have methods like “read_contents”, “write_contents” (plus > maybe atomic write, append, etc. variants) that you often use, and you only > use it as a context manager if you want to get an iterable of lines out of > it or something else you can access iteratively rather than all at once. > > > > If __enter__ is the place where all resources are allocated, then the > constructor has to record file name (and dirfd), whether to open for > reading or writing, the encoding/errors, and everything else you need > to know before you can open it. Basically it'd have to record all the > arguments to open(), plus any additional state required (current > directory, perhaps) in case it can change. The "file ready to be > opened" would have to actually be "this file, to be read from in UTF-8 > mode and not written to". > > I think it'd be at least as confusing as the current situation. > >
Real world example: isn't something like this what happens with click.File?
_______________________________________________ Python-ideas mailing list -- python-ideas@python.org To unsubscribe send an email to python-ideas-le...@python.org https://mail.python.org/mailman3/lists/python-ideas.python.org/ Message archived at https://mail.python.org/archives/list/python-ideas@python.org/message/QEJ4URV725LYCVNGCDBEK6F277IV76W6/ Code of Conduct: http://python.org/psf/codeofconduct/
