#4148 add values_at method for CSV::Row

[need47]

This PR adds the following methods to CSV::Row in (src/csv.cr)

values_at(*columns : Int)
values_at(*headers: String)

to retrieve multiple values at given columns or corresponding to headers.

A spec file was also provided at: spec/std/csv/csv_values_at_spec.cr

It's my first PR ever. If I was doing something wrong, please kindly let me know

[Sija]

self[column]

[Sija]

ditto

[need47]

@Sija I have updated the PR according to your comment. My local test was good, but I saw that Travis CI had failed. Not sure whether it's related to my PR. Let me know if there is anything I can do.

[bcardiff]

Hi @need47, the failures are because of formatting.

If you run

$ crystal tool format spec/std/csv/csv_values_at_spec.cr
$ crystal tool format src/csv.cr

There should be changes to submit and will make CI pass. At least linux one. There are currently some issues regarding OSX CI.

[need47]

All checks passed except for OSX CI. Just FYI, I did compile LLVM (version 3.9.1) without the OSX platform.

[need47]

I am reading the spec/std/csv/csv_spec.cr and found an interesting use of CSV.

it "can do new with block" do
    CSV.new(%(one, two\n1, 2\n3, 4\n5), headers: true, strip: true) do |csv|
      csv["one"].should eq("1")
      csv["two"].should eq("2")
      break
    end
  end

a csv object can call [] directly as if it was a row. So shall I also add CSV#values_at() methods, in addition to CSV::Row#values_at() in this PR?

[bcardiff]

@need47 Sure! mimic how row_internal is used in the other [] methods.

[need47]

I have added CSV#values_at and CI passed.

[bcardiff]

@need47 Sorry, I've just noticed that the specs should be at spec/std/csv/csv_spec.cr, would you move them when you have time?

[need47]

specs moved and CI passed.

[bcardiff]

Merged! Thanks @need47 for your first contribution to crystal