Reading String Data as a File
in [Ruby]
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From: Brian Candler on 30 Jun 2010 10:55 Robert Klemme wrote: > At least one can use Tempfile for this, e.g. > > Tempfile "prefix", "/tmp" do |io| > io.write everything > > io.seek 0 > whatever_load_routine io > end or rather: Tempfile.open "prefix", "/tmp" do |io| io.write everything io.flush whatever_load_routine io.path end -- Posted via http://www.ruby-forum.com/.
From: James Edward Gray II on 30 Jun 2010 11:05 On Jun 30, 2010, at 7:53 AM, Brian Candler wrote: > Robert Klemme wrote: >> This is an interesting point of interface design: usually it is more >> convenient to just pass a file name somewhere and that method opens >> the file (or URL) and reads the data. But from a modularity point of >> view it is generally better to pass an open IO like instance. > > Definitely. The original csv.rb in ruby 1.8 got this very badly wrong. > > The new (faster_csv) interface is capable of this, but it suffers from > missing documentation. I agree that FasterCSV's documentation isn't perfect. I'm pretty sure all of its functions are documented, but you would need to read the API like a novel to find them. I've been trying more tutorial style documentation lately, but there again it's hard to reference what you specifically want to know. I'm open to suggestions and I do take patches. > IIRR you have to do something like > > FasterCSV.new($stdin).each do |row| > p row > end That works, yes. > Since the documented "primary" interface is > FasterCSV.foreach("path/to/file.csv"), you have to dig through the code > to work out how to handle an open stream. That's mostly due to a pet peeve of mine. I often see code that slurps when foreach() would have worked fine. That's why I try to push that as a first choice. Do you think it would help if I added Wrapping an IO under the Shortcut Interface on this page? http://fastercsv.rubyforge.org/classes/FasterCSV.html James Edward Gray II
From: Robert Klemme on 30 Jun 2010 11:09 2010/6/30 Brian Candler <b.candler(a)pobox.com>: > Robert Klemme wrote: >> At least one can use Tempfile for this, e.g. >> >> Tempfile "prefix", "/tmp" do |io| >> io.write everything >> >> io.seek 0 >> whatever_load_routine io >> end > > or rather: > > Tempfile.open "prefix", "/tmp" do |io| > io.write everything > io.flush I'd rather io.close instead of io.flush to release resources as soon as possible. > whatever_load_routine io.path > end Ooops! Yes, of course. I copied the wrong example. Sorry for my confusion. Cheers robert -- remember.guy do |as, often| as.you_can - without end http://blog.rubybestpractices.com/
From: Brian Candler on 30 Jun 2010 11:31 Robert Klemme wrote: > 2010/6/30 Brian Candler <b.candler(a)pobox.com>: >> or rather: >> >> Tempfile.open "prefix", "/tmp" do |io| >> �io.write everything >> �io.flush > > I'd rather io.close instead of io.flush to release resources as soon > as possible. But tempfile will want to close itself using the block form anyway. In most versions of ruby, Tempfile with a block returns nil. A change was committed so that it returns the (closed) object, but that hasn't made it into either of the versions I have lying around here. >> tf = Tempfile.open("aaa","/tmp") { puts "hello"; 123 } hello => nil -- Posted via http://www.ruby-forum.com/.
From: Brian Candler on 30 Jun 2010 11:41
James Edward Gray II wrote: > I'm open to suggestions and I do take patches. Specifically, I'd like to see how to parse CSV from stdin. You provide an example in the opposite direction: # FCSV($stderr) { |csv_err| csv_err << %w{my data here} } # to $stderr A bit more experimentation suggests that FCSV($stdin).each { |a,b,c| p a,b,c } works, so if that's a reasonable way to drive the library, I'd like to see that mentioned under shortcuts. (I thought I'd tried that before and it failed, but I must have done something different) -- Posted via http://www.ruby-forum.com/. |