Reusing chunks of code

ruby-talk
1

Hi guys,

I wanted to avoid using the word "block" as it's such a key word in Ruby.
I'm performing the same test twice here and there must be a way to
reuse it...
=begin
Mon Jan 21 12:51:19 GMT 2008
simple plays with dirs
=end

# create a "singleton object"
testobj = Object.new

# play with the object - just a start :wink:
def testobj.homePlay
  startDir = Dir.pwd
  p "current dir is #{startDir}"
  puts "Dir.getwd == Dir.pwd" if Dir.getwd == Dir.pwd

# check for ~/
  if Dir.exist?("#{ENV["HOME"]}")
    p "changing to ~/"
  else
    p "cannot find your home dir. STOP!"
    exit
  end

  Dir.chdir

# have we changed directory from where we started?
  if Dir.pwd == startDir
    p "current dir is still #{startDir}. pwd not changed ;-)"
  else
    p "pwd has changed to Dir.pwd"
  end

  print "file listing of your home dir...\n\n"

  p Dir.entries(".").sort # << this an array
  print "\n\nlisting ../ \n\n"
  Dir.foreach("..") {|x| p x}

end
# end of method testobj.dirPlay

def testobj.procPlay
  px = "/proc/"
  if Dir.exist?("#{px}")
    p "#{px} dir found - continue"
  else
    p "#{px} not found - STOP!"
    exit
  end
end

# send message to object
testobj.homePlay
testobj.procPlay

__END__
The question is how to reuse the "testing if directory exists chunk of code"? I'm still thinking procedurally I guess.
Regards,

John Maclean
MSc (DIC)
+44 7739 171 531

2

John Maclean wrote:

Hi guys,

I wanted to avoid using the word "block" as it's such a key word in
Ruby.
I'm performing the same test twice here and there must be a way to
reuse it...
=begin
Mon Jan 21 12:51:19 GMT 2008
simple plays with dirs
=end

# create a "singleton object"
testobj = Object.new

# play with the object - just a start :wink:
def testobj.homePlay
  startDir = Dir.pwd
  p "current dir is #{startDir}"
  puts "Dir.getwd == Dir.pwd" if Dir.getwd == Dir.pwd

# check for ~/
  if Dir.exist?("#{ENV["HOME"]}")
    p "changing to ~/"
  else
    p "cannot find your home dir. STOP!"
    exit
  end

  Dir.chdir

# have we changed directory from where we started?
  if Dir.pwd == startDir
    p "current dir is still #{startDir}. pwd not changed ;-)"
  else
    p "pwd has changed to Dir.pwd"
  end

  print "file listing of your home dir...\n\n"

  p Dir.entries(".").sort # << this an array
  print "\n\nlisting ../ \n\n"
  Dir.foreach("..") {|x| p x}

end
# end of method testobj.dirPlay

def testobj.procPlay
  px = "/proc/"
  if Dir.exist?("#{px}")
    p "#{px} dir found - continue"
  else
    p "#{px} not found - STOP!"
    exit
  end
end

# send message to object
testobj.homePlay
testobj.procPlay

__END__
The question is how to reuse the "testing if directory exists chunk of
code"? I'm still thinking procedurally I guess.
Regards,

John Maclean
MSc (DIC)
+44 7739 171 531

  puts "Dir.getwd == Dir.pwd" if Dir.getwd == Dir.pwd

According to my book, getwd() and pwd() are the same method.

  if Dir.exist?("#{ENV["HOME"]}")

Dir.exist? I don't have that method. Is it new?

The question is how to reuse the "testing if directory exists chunk of
code"? I'm still thinking procedurally I guess.

Do you mean this part:

  if Dir.exist?("#{ENV["HOME"]}")
    p "changing to ~/"
  else
    p "cannot find your home dir. STOP!"
    exit
  end

You could write:

def check_dir(some_str)
  if Dir.exist?(some_str)
      p "changing to ~/"
    else
      p "cannot find your home dir. STOP!"
      exit
  end
end

but that isn't very general since you hardcoded the message to output.
You could pass two messages in as arguments, but really what does the
output message have to do with checking whether the dir exists? So that
leaves you with something like this:

def check_dir(some_str)
  return Dir.exist?(some_str)
end

And you could write:

if check_dir("some dir")
    puts 'yep'
else
    puts 'nope'
end

But that code just wraps a definition around a ruby method, so why not
just call the method directly--like you did in the first place:

if Dir.exist?("some dir")
   puts 'yep'
else
   puts 'nope'
end

···

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