Bug #15910
closed$. doesn't hold the linenumber anymore when reading a CSV-file using the CSV class
Description
Example program:
require 'csv'
IFS=';'
CSV_OPTIONS = { col_sep: IFS, external_encoding: Encoding::ISO_8859_1, internal_encoding: Encoding::UTF_8 }
CSV.new($stdin, CSV_OPTIONS).each do
|row|
puts "::::line #{$.} row=#{row}"
end%
With this program, I could dump a semicolon-delimited CSV file, with line numbers. Now the line number always displays as 0. Has the implementation of CSV changed?
See also https://stackoverflow.com/questions/56524941/is-special-variable-gone-from-ruby
Updated by jeremyevans0 (Jeremy Evans) over 5 years ago
- Assignee set to kou (Kouhei Sutou)
I can confirm the behavior change. I bisected it to https://github.com/ruby/csv/commit/8505ff0900a4789dce0740ab23e92de1fb89196e. I would not consider this change a bug, since I don't think the csv library was ever documented as treating $.
as the line number of the current CSV file. I would consider it relying on internal behavior. Restoring backwards compatibility in regards to $.
looks like it may hurt performance. Assigning to kou, csv maintainer, to make a decision.
Updated by kou (Kouhei Sutou) over 5 years ago
- Status changed from Open to Rejected
CSV implementation was changed to improve performance. The new implementation reads data as chunk ($stdin.gets(nil, 4096)
) instead of lines ($stdin.gets
) from input. $.
doesn't work with reading data as chunk.
It's backward incompatible but I don't want to keep the previous behavior. Because it blocks performance improvement.
You can use CSV#lineno
as alternative:
require 'csv'
IFS=';'
CSV_OPTIONS = { col_sep: IFS, external_encoding: Encoding::ISO_8859_1, internal_encoding: Encoding::UTF_8 }
csv = CSV.new($stdin, CSV_OPTIONS)
csv.each do |row|
puts "::::line #{csv.lineno} row=#{row}"
end
CSV#lineno
reports logical line number. If your CSV data has a record that includes new lines:
a;"with
new
line"
b;c
CSV#lineno
reports 1
for a;"with\nnew\nline"
row and 2
for b;c
row.
If your CSV data doesn't have these rows, you can use CSV#lineno
as alternative of $.
.