What it exactly do these do ( RubyXL::Parser.parse and Roo::Excelx.new) when opening a file?

alcina · October 21, 2013, 5:36pm

Do they open a file and load it into memory?

I’m asking because it seems to take a long time opening a file but after
it
opens looping into the variable is REALLY fast, could someone explain me
or
tell me where can I find an explanaition on how this sort of things
work?

Monserrat_F · October 21, 2013, 5:52pm

Usually the simplest way to learn how a gem works internally is to go
and read the source code. This should be available in the gem files, on
a github repository, or in the documentation.

Monserrat_F · October 21, 2013, 6:00pm

I haven’t examined Roo, but you can see RubyXL reading the file into
memory here:

github.com

weshatheleopard/rubyXL/blob/master/lib/rubyXL/parser.rb

module RubyXL
  class Parser
    # Parse <tt>.xslx</tt> file by reading it from local disk.
    def self.parse(src_file_path)
      begin
        ::Zip::File.open(src_file_path) { |zip_file|
          root = RubyXL::WorkbookRoot.parse_zip_file(zip_file)
          root.source_file_path = src_file_path
          root.workbook
        }
      rescue ::Zip::Error => e
        raise e, "XLSX file format error: #{e}", e.backtrace
      end
    end

    # Parse <tt>.xslx</tt> file contained in a stream (useful for receiving over HTTP).
    def self.parse_buffer(buffer)
      root = nil # Zip::File.open_buffer somehow fails to return the value from the block :(
      begin
        ::Zip::File.open_buffer(buffer) { |zip_file| root = RubyXL::WorkbookRoot.parse_zip_file(zip_file) }

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Monserrat_F · October 21, 2013, 6:01pm

I’m asking because I’m new to both ruby and rails and my knowledge is
not
enough to understand source code