Question

Can this line of code be made more compact?

db_tables_scanned = {}
IO.readlines(resume_log_file).each { |db_table| db_tables_scanned[db_table.split(".")[0].strip] << db_table.split(".")[1].strip if db_table.include? '.' } if resume and File.exists?(resume_log_file)

Answer 1

You want a one-liner? Here’s a one-liner:

db_tables_scanned = resume and File.exists?(resume_log_file) ? Hash[IO.readlines(resume_log_file).map { |db_table| db_table.split(".").map(&:strip) if db_table.include? '.' }.compact] : {}

Of course this code is hideous. There is no need to get obsessed about getting less lines of code. Code has to:

1. Be human-readable
2. Use the most fitting and idiomatic abstractions of the language.

In this case, let’s break it in lines, and use a Hash[pairs_of_keys] to build the hash:

db_tables_scanned = if resume and File.exists?(resume_log_file)
  Hash[IO.readlines(resume_log_file).map do |db_table|
    if db_table.include?('.')
      db_table.split(".").first(2).map(&:strip)
    end  
  end.compact]
else
  {}
end