From: Robert Klemme <shortcutter@...>
Date: 2008-08-19T23:51:40+09:00
Subject: Re: reading x bytes at a time

On 19 Aug., 02:21, Matt Harrison <iwasinnamuk...@genestate.com> wrote:
> I've just played around and found this seems to work:
>
> File.open(path, "r") do |fh|
>   while (chunk = fh.read(blocksize))
>     outFH.puts Digest::MD5.hexdigest(chunk) + "\n"
>   end
> end
>
> Is this a good way to do it?

Somehow my posting from today morning neither made it to Google news
nor the mailing list.  Strange...

To sum it up: yes, that's a good way to do it.  Few remarks:

You do not need + "\n" because #puts will do this already.

I prefer to open with "rb" instead of "r" in these cases.  Makes
scripts more portable plus helps documenting that this is really a
binary stream.

You can preallocate the buffer, this saves a bit of GC:

File.open(path, "rb") do |fh|
  chunk = ""
  while fh.read(blocksize, chunk)
    outFH.puts Digest::MD5.hexdigest(chunk)
  end
end

Kind regards

robert