From: Ryan Davis <ryand-ruby@...>
Date: 2009-12-14T08:18:48+09:00
Subject: Re: case with && not working compared to using if, works!


On Dec 13, 2009, at 12:22 , Derek Smith wrote:

> hasval = pidhash.value?(7)          ### store true/false
> case hasval
>    when true
>        then
>        puts("Running PID == PID in File
> ".+(d.to_s).+(t.hour.to_s).+(t.min.to_s))
>    when (false && File.size(PIDF) == 1)
>        then
>        puts "2nd. PID not active yet file exists", PIDF
>    when (false && File.size(PIDF) == 0)
>        then
>        puts "3rd"
>    else
>        puts "no con met"
>        exit
> end

It just doesn't work this way. It is nonsensical. Stick to your if/elsif/else and things will work fine.

About the nonsensical:

  case x
  when a
  when b
  ...

is roughly equivalent to:

  if    a === x
  elsif b === x
  ...

So what does this mean?

  case hasval
  when (false && File.size(PIDF) == 1)

it roughly translates to:

  if (false && File.size(PIDF) == 1) === hasval

or by logical deduction:

  if false === hasval

Which I doubt you meant.

Again, stick to simple if/elsif/else statements and you'll be happier.

Also, your code drives me bonkers. Check it:

puts("Running PID == PID in File ". +(d.to_s). +(t.hour.to_s). +(t.min.to_s))

is about as pedantically awkward as you can get. Dot notation for the + operator?? NO!

At worst it should be:

puts "Running PID == PID in File " + d.to_s + t.hour.to_s + t.min.to_s

Hey look! My space bar works! Also, My pinkies aren't so tired by typing so many parens!

Even better, use interpolation:

puts "Running PID == PID in File #{d}#{t.hour}#{t.min}"

(tho that looks like it'll print out ugly, it is equivalent to your original code and is much more readable.)