From: Phrogz <phrogz@...>
Date: 2007-11-07T01:30:24+09:00
Subject: Re: why return gives error when used with ? :

Others have pointed out that (in this particular example) it's foolish
to branch on a boolean value only to return that particular value as a
new literal, so here's a modified test showing the fastest way - just
let the boolean value return itself.


require 'benchmark'

def ternary_return1( x )
  return ( x==5 ? true : false )
end

def ternary_return2( x )
  x==5 ? (return true) : (return false)
end

def if_return1( x )
  return (if x == 5
    true
  else
    false
  end)
end

def if_return2( x )
  if x == 5
    return true
  else
    return false
  end
end

def ternary_expression( x )
  x == 5 ? true : false
end

def if_expression( x )
  if x == 5
    true
  else
    false
  end
end

def boolean_expression( x )
  x == 5
end

def return_boolean( x )
  return x == 5
end

values = (1..8).to_a * 1_000_000
method_names = %w| ternary_return1 ternary_return2
                   if_return1 if_return2
                   ternary_expression if_expression
                   boolean_expression return_boolean |

Benchmark.bmbm{ |x|
  method_names.each{ |name|
    meth = method( name )
    x.report( name ){
      values.each{ |n|
        meth.call( n )
      }
    }
  }
}


Rehearsal ------------------------------------------------------
ternary_return1     12.125000   0.000000  12.125000 ( 12.172000)
ternary_return2     11.750000   0.000000  11.750000 ( 11.812000)
if_return1          11.797000   0.000000  11.797000 ( 11.813000)
if_return2          11.453000   0.000000  11.453000 ( 11.484000)
ternary_expression  10.516000   0.000000  10.516000 ( 10.578000)
if_expression       11.218000   0.000000  11.218000 ( 11.250000)
boolean_expression   9.719000   0.000000   9.719000 (  9.782000)
return_boolean      10.797000   0.000000  10.797000 ( 10.812000)
-------------------------------------------- total: 89.375000sec

                         user     system      total        real
ternary_return1     11.578000   0.000000  11.578000 ( 11.625000)
ternary_return2     12.141000   0.000000  12.141000 ( 12.188000)
if_return1          11.765000   0.000000  11.765000 ( 11.812000)
if_return2          12.031000   0.000000  12.031000 ( 12.078000)
ternary_expression  10.969000   0.000000  10.969000 ( 10.999000)
if_expression       11.078000   0.000000  11.078000 ( 11.125000)
boolean_expression  10.093000   0.000000  10.093000 ( 10.125000)
return_boolean      11.141000   0.000000  11.141000 ( 11.188000)