From: "Ara.T.Howard" <ahoward@...>
Date: 2004-06-20T05:43:19+09:00
Subject: Re: [RCR] IO#readn

On Sun, 20 Jun 2004, Michael Neumann wrote:

> On Sun, Jun 20, 2004 at 01:33:18AM +0900, Ara.T.Howard wrote:
>> On Sun, 20 Jun 2004, Michael Neumann wrote:
>>
>>> Hi,
>>>
>>> I suggest to add a method readn to the IO class (and to StringIO,
>>> Socket...), which behaves similar to read(n), but raises an exception if
>>> the returned string is not of size n.
>>>
>>> class IO
>>>   def readn(n)
>>>     str = read(n)
>>>     raise if str.nil? or str.size != n
>>>     str
>>>   end
>>> end
>>>
>>> It's annoying to test for it in the application.
>>>
>>> Regards,
>>>
>>> Michael
>>
>> don't you think the code will be just as long/annoying with a begin/rescue
>> block?
>
> No, as I wouldn't use a rescue clause in this case. It's better to crash
> early than proceed with a wrong value.
>
> I never liked it that read(4) might return only 3 characters.
>
> Regards,
>
>  Michael

but another read may give one more byte - then you'd have your 4?  even if one
implemented IO#read(n) i'd think you'd want:

   class IO
     def readn n
       buf = ''
       buf << read(n - buf.size) until buf.size == n
       buf
     end
   end

which give you what you want (n bytes), or throws EOFError.

-a
--
===============================================================================
| EMAIL   :: Ara [dot] T [dot] Howard [at] noaa [dot] gov
| PHONE   :: 303.497.6469
| A flower falls, even though we love it; and a weed grows, even though we do
| not love it. --Dogen
===============================================================================