[ruby-core:27931] Re: [Bug:trunk] some behavior changes of lib/csv.rb between 1.8 and 1.9

On Jan 28, 2010, at 10:51 AM, Yusuke ENDOH wrote:

> Hi jeg2, or anyone who knows the implementation of FasterCSV,

Hello.

> I'm now checking for ruby trunk to pass rubyspec.  Are these behavior
> changes of lib/csv.rb intended or bug?

Yes, they are intentional changes.

> 1) CSV.generate
> 
> $ ruby18 -rcsv -e 'w = CSV.generate("foo18.csv"); w << [1, 2, 3]; w.close'
> $ cat foo18.csv
> 1,2,3
> 
> $ ruby19 -rcsv -e 'w = CSV.generate("foo19.csv"); w << [1, 2, 3]; w.close'
> /home/mame/work/ruby19/local/lib/ruby/1.9.1/csv.rb:1231:in
> `generate': no block given (yield) (LocalJumpError)
>         from -e:1:in `<main>'
> 
> There is the comment of csv.rb:
>> The old CSV's Reader and Writer classes have been dropped.
>> CSV::generate() is different from the old method.
> They mean this change, don't they?

Yes, I believe generating to a file was even deprecated in CSV, if I remember correctly.  In either case, FasterCSV doesn't support it.

> 2) CSV.generate_line
> 
> $ ruby18 -rcsv -e 'p CSV.generate_line([])'
> ""
> 
> $ ruby19 -rcsv -e 'p CSV.generate_line([])'
> "\n"

This is intentional.  FasterCSV always generates a complete line, including the :row_sep.

> 3) CSV.generate_line (2)
> 
> $ ruby18 -rcsv -e 'p CSV::generate_line(["foo", "bar"], ?;)'
> "foo;bar"
> 
> $ ruby19 -rcsv -e 'p CSV::generate_line(["foo", "bar"], ?;)'
> /home/mame/work/ruby19/local/lib/ruby/1.9.1/csv.rb:1249:in `merge':
> can't convert String into Hash (TypeError)
>         from /home/mame/work/ruby19/local/lib/ruby/1.9.1/csv.rb:1249:in
> `generate_line'
>         from -e:1:in `<main>'

Yes, FasterCSV got rid of the positional arguments in favor of keyword arguments.  So, it's now:

  CSV.generate_line(%w[foo bar], :row_sep => ?;)

> 3) CSV.parse
> 
> $ ruby18 -rcsv -ve 'p CSV.parse "\nfoo"'
> [[nil], ["foo"]]
> 
> $ ruby19 -rcsv -ve 'p CSV.parse "\nfoo"'
> [[], ["foo"]]

Yeah, the old CSV included some seemingly random nils in places.  FasterCSV "corrects" this odd behavior.

> 4) CSV.parse_line
> 
> $ ruby18 -rcsv -ve 'p CSV.parse_line ""'
> [nil]
> 
> $ ruby19 -rcsv -ve 'p CSV.parse_line ""'
> nil

We could probably debate this one.  It may be that FasterCSV should return a [] instead of nil.  I'll make a not to look into that and maybe fix it. We won't be going back to the CSV response of [nil] though, since I don't understand it.  (See my answer to #3.)

> 5) CSV.parse_line (2)
> 
> $ ruby18 -rcsv -ve 'p CSV.parse_line "\nfoo"'
> [nil]
> 
> $ ruby19 -rcsv -ve 'p CSV.parse_line "\nfoo"'
> []

parse_line() only reads the first line, so this is the same as #3.

James Edward Gray II