From: John Crichton <a2533488@...>
Date: 2010-07-10T13:30:59+09:00
Subject: if statements and case statements questions

I am fairly new to Ruby and programming and had a couple questions about
if/else and case statements.  I was wondering if there were benefits to
using case statements instead of if/elsif/else type statements.  Are
case statements faster?

If I am reading in a file line by line and doing something similar to

lines = File.open("file.csv")
FasterCSV.parse(lines) do |row|
  if ( lines =~ /^blah/)

    puts "blahblahblah"
    some_method
  end

  if ( lines =~ /^name/ && row[1] =="123")
    puts "ping pong abc"
    another_method
  end
  if ( lines =~ /^address/ && row[3] =="XYZ")
    puts "abcdefghijklmnopqrstuvwxyz"
    method3
  end
end

Does writing it with a case statement like so benefit me?
lines = File.open("file.csv")
FasterCSV.parse(lines) do |row|
  case
  when ( lines =~ /^blah/)
    puts "blahblahblah"
    some_method

  when ( lines =~ /^name/ && row[1] =="123")
    puts "ping pong abc"
    another_method

  when ( lines =~ /^address/ && row[1] =="XYZ")
    puts "abcdefghijklmnopqrstuvwxyz"
    method3
  end
end

While writing this I couldn't figure out how to write my case to be "if
lines begins with"
  case "lines =~"
  when /^blah/
    puts "blahblahblah"
    some_method

Lastly is there a "better" way to write an if statement that is
conditional on a bunch of things like
  if row[0] == john && row[7] == abc123  && row[8] != nil &&
somehashtable.has_key?(row2)

Thanks
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