What is "p" in Ruby?

ruby printf-debugging
James P. Wright picture James P. Wright · Nov 18, 2009 · Viewed 20.6k times · Source

I'm sure it's a silly question to those who know, but I can't find an explanation of what it does or what it is.

CSV.open('data.csv', 'r') do |row|
  p row
end

What does "p row" do?

Answer

DigitalRoss picture DigitalRoss · Nov 18, 2009

p() is a Kernel method

It writes obj.inspect to the standard output.

Because Object mixes in the Kernel module, the p() method is available everywhere.

It's common, btw, to use it in poetry mode, meaning that the parens are dropped. The CSV snippet can be written like...

CSV.open 'data.csv', 'r' do |row|
  p row
end

It's documented here with the rest of the Kernel module.

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