Add CSV::TSV class for tab-separated values

[jsxs0]

Add TSV class for tab-separated files support

This PR adds a lightweight TSV class that provides first-class support for tab-separated files through a simple inheritance mechanism from the CSV class.

Implementation

The implementation has been simplified to only override the initialize method, which sets the default column separator to tab (\t). This minimalist approach maintains full compatibility with CSV while providing convenient TSV handling:

class TSV < CSV
  def initialize(data, **options)
    super(data, **({col_sep: "\t"}.merge(options)))
  end
end

Features

• Inherits all functionality from CSV class
• Uses tab as the default separator
• Allows override of separator if needed
• Maintains full interface compatibility with CSV
• Zero additional maintenance overhead due to minimal implementation

Example Usage

# Read TSV file with default tab separator
TSV.read("data.tsv")

# Parse TSV string
TSV.parse("a\tb\tc")

# Generate TSV content
TSV.generate do |tsv|
  tsv << ["a", "b", "c"]
  tsv << [1, 2, 3]
end

# Override separator if needed (though you might want to use CSV directly in this case)
TSV.read("data.csv", col_sep: ",")

Motivation

This change is motivated by:

• Providing better support for TSV files without adding complexity
• Making tab-separated file handling more convenient through a dedicated class
• Following the principle of least surprise - users expect TSV to use tabs by default

(https://github.com/ruby/csv/issues/272)

Changes from Previous Version

The implementation has been significantly simplified:

• Removed unnecessary method overrides
• Now only overrides initialize to set default separator
• Maintains full CSV functionality through inheritance
• Added comprehensive test coverage

[kou]

Hmm. Do we need to override all class methods? Can we just override TSV#initialize?

diff --git a/lib/csv.rb b/lib/csv.rb
index f6eb32a..8c71b4d 100644
--- a/lib/csv.rb
+++ b/lib/csv.rb
@@ -2979,6 +2979,12 @@ class CSV
   end
 end

+class TSV < CSV
+  def initialize(data, **options)
+    super(data, **({col_sep: "\t"}.merge(options)))
+  end
+end
+
 # Passes +args+ to CSV::instance.
 #
 #   CSV("CSV,data").read

BTW, is CSV::TSV intentional? (::TSV may be easy to use but it may break other library's API that defines ::TSV...)

[jsxs0]

@kou Thanks for the feedback! Updated and pushed a new commit.

[kou]

Could you add some tests for this change? Could you update the PR description for the latest changes?

[jsxs0]

Could you add some tests for this change? Could you update the PR description for the latest changes?

@kou Thanks, added tests and updated the description.

[kou]

Did you run added tests on your local machine? Or did you enable GitHub Actions on your fork?

We need to add CSV:: to all TSV references.

[jsxs0]

Did you run added tests on your local machine? Or did you enable GitHub Actions on your fork?

We need to add CSV:: to all TSV references.

Thanks. The fix was a straightforward namespace correction that aligns the test code with the actual implementation in lib/csv.rb.

[kou]

Thanks.