From: kwatch <kwatch@...>
Date: 2008-09-18T00:52:43+09:00
Subject: Re: Q: IO.read() and IO.write()

Thank you, Matz.

2008/09/17 Yukihiro Matsumoto <m...@ruby-lang.org> wrote:
> |* Why is IO.read(filename) defined?
> |  IMO, File.read() is more natural than IO.read() because
> |  IO class is not related to filename, I think.
>
> No big reason.  Historically IO works on files, i.e.  IO.open(path),
> so that it was natural to provide these methods in IO too.

File.open() is different from IO.open().
IO.open(fd) takes file descriptor as argument,
while File.open(filename) takes filename.

irb(main):012:0> File.open('/tmp/hoge.txt') {|f| f.read }
=> "foo"
irb(main):013:0> IO.open('/tmp/hoge.txt') {|f| f.read }
TypeError: can't convert String into Integer
        from (irb):13:in `initialize'
        from (irb):13:in `open'
        from (irb):13

IO.open() can't take filename as argument, so it is odd for me
that IO.read() is defined in IO class, not File class.


>
> |* Is there any reason that IO.write() (or File.write()) is not
> |provided?
> |  I have to define File.write() for each project...
> |  It is easy to define File.write() but I hope it is provided by Ruby.
>
> For File.read(), when you want to specify file mode, you can just say:
>
>   File.read(path, "rb")

Ruby's manual says that 2nd argument of File.read() is length to read.

irb(main):016:0> File.read('/tmp/hoge.txt')
=> "foo"
irb(main):017:0> File.read('/tmp/hoge.txt', 2)
=> "fo"
irb(main):018:0> File.read('/tmp/hoge.txt', 'rb')    # ERROR!
TypeError: can't convert String into Integer
        from (irb):17:in `read'
        from (irb):17

>
> For File.write(), it is more likely to be:
>
>   File.write(path, str, "wb")
>
> which makes me feel weird.  In 1.9, we can write
>
>   File.write(path, str, mode: "wb")
>
> which I feel slightly better.
>                                                         matz.

You mean that there is no plan to add File.write() in Ruby 1.9?

--
regards,
makoto kuwata