From: "NAKAMURA, Hiroshi" <nakahiro@...>
Date: 2006-06-05T09:55:03+09:00
Subject: Re: FasterCSV RCR?

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Hi,

James Edward Gray II wrote:
>> James Edward Gray II wrote:
>>> method arguments, we could get pretty close to perfect, but CSV does
>>> some odd things like confuse open() with foreach() that I chose to avoid
>>> in FasterCSV.  Because of that, I can't always be sure what to do when
>>
>> Can you please explain what are "odd"?
> 
> My biggest complaint with CSV is that open() behaves "oddly" and thus
> defeats all my normal expectations:
> 
>>> File.open("example.csv", "w") do |csv|
> ?>   csv.puts "1,2,3"
>>>   csv.puts "a,b,c"
>>> end
> => nil
>>> require "csv"
> => true
>>> # typical Ruby style reading...
> ?> File.open("example.csv") do |file|
> ?>   file.each { |row| p row }
>>> end
> "1,2,3\n"
> "a,b,c\n"
> => #<File:example.csv (closed)>
>>> # or...
> ?> File.foreach("example.csv") do |row|
> ?>   p row
>>> end
> "1,2,3\n"
> "a,b,c\n"
> => nil
>>> # CSV's "odd" open() method...
>>> CSV.open("example.csv", "r") do |row|  # "r" required
> ?>   p row  # we get rows, not the file object
>>> end
> ["1", "2", "3"]
> ["a", "b", "c"]
> => nil
> 
> Of course, if you open in a writing mode, you do get a file like
> object.  It's inconsistent.

I can understand your frustration about this point.  When I wrote csv.rb
at first, I thought all csv users would do the following when I define
reader style.

  CSV.open("filename.csv", "r") do |reader|
    reader.each do |row|
      ...do something...
    end
  end

Why don't we just write like this;

  CSV.open("filename.csv", "r") do |row|
    ...do something...
  end

I know you are considering that IO-ish methods are important.  But I
don't think CSV object should handle IO methods like fcntl, fileno,
seek, tell, tty?, and so on.  Would you please tell me typical and
pragmatic examples of reader style, except 'each'?

> I'm confused about why CSV does this, since it offers the foreach()
> method, which normally fills this role.

foreach and readlines are added recently from IO.  Now I think it was a
bad choice though...

> Other CSV oddities (my opinion):

Thanks!

> *  I always have to think, "Now do I want the *_line() method or the
> *_row() method here..."

Users don't need to use *_line and *_row methods I think.  When do you
use generate_line?

> *  Most methods take a field separator and a row separator, but
> foreach() and readlines() only take the row separator.

See IO.foreach and IO.readlines.  But as I wrote above, CSV should not
have these methods...

> *  I have to set a field separator when I really just want to set a row
> separator.

csv.rb in svn repository supports pseudo-keyword-like-method-argument
style.  I'll merge it ruby's csv repository before the next release.
http://dev.ctor.org/csv/browser/trunk/lib/csv.rb

# I defined keywords :fs and :rs but it should be :col_sep and :row_sep
# in conformity with faster_csv.

> *  A method called "generate_line()" doesn't involve a line ending.

Do not use it. :-)  At least users rarely use it I think.

I hope that
  csv.rb's open + read + block does not work as you expected
is the only and the big frustrated point of csv.rb (...if csv.rb is
enough faster :-)

>>> 2.  We could drop compatibility and rename FasterCSV to CSV.  This way
>>> people get all the good stuff where they expect it.  However, this would
>>
>> Can you please explain what are "good"?  I'll introduce those features
>> into csv.rb.
> 
> Here's a selection of some features from my CHANGELOG that I am not
> aware of in CSV:

Thanks.  I'll look into this.  I hope those features are pluggable into
csv.rb and other modules like DBI, spreadsheet related things, HTML
table formatters, etc.  I think some of these features are table
specific, not CSV.

Regards,
// NaHi
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