/ex3

## ex3
# Exercise: write a proc that provides content for the following html template:
def template
template =<<DELIM
<html>
<head>
#{yield :header}
</head>
<body>
#{yield}
<hr>
<p>
#{yield :footer}
</p>
</body>
</html>
DELIM
return template
end

content_definitions = proc {|x|
	text = "<p> body text</p>"
	if (x.eql?:"header")
	  text = "<title>The Title Defintion</title>"
	end
	if(x.eql?:"footer")
	  text = "<p>This could be a footer.</p>"
	end

	text
}

puts template &content_definitions


# procs are closures!
# that is, they preserve the variable bindings from the place where they are defined.

#extend create_counter such that it returns two procs, one for #increasing, one for decreasing the counter.


class Counter
  @@n = 0
  @@counter = 0

  def self.create_counter
    @@counter+=1
    if (@@counter%2==1)
      proc { @@n+=1 }
    else
      proc { @@n-=1 }
    end
  end
end

first_counter = Counter.create_counter
puts "first_counter.call #{first_counter.call}"
puts "first_counter.call #{first_counter.call}"

second_counter = Counter.create_counter
puts "second_counter.call #{second_counter.call}"
puts "first_counter.call #{first_counter.call}"
puts "second_counter.call #{second_counter.call}"
puts "first_counter.call #{first_counter.call}"
	# Exercise: write a proc that provides content for the following html template:
	def template
	template =<<DELIM
	<html>
	<head>
	#{yield :header}
	</head>
	<body>
	#{yield}
	<hr>
	<p>
	#{yield :footer}
	</p>
	</body>
	</html>
	DELIM
	return template
	end

	content_definitions = proc {\|x\|
	text = "<p> body text</p>"
	if (x.eql?:"header")
	text = "<title>The Title Defintion</title>"
	end
	if(x.eql?:"footer")
	text = "<p>This could be a footer.</p>"
	end

	text
	}

	puts template &content_definitions



	# procs are closures!
	# that is, they preserve the variable bindings from the place where they are defined.

	#extend create_counter such that it returns two procs, one for #increasing, one for decreasing the counter.


	class Counter
	@@n = 0
	@@counter = 0

	def self.create_counter
	@@counter+=1
	if (@@counter%2==1)
	proc { @@n+=1 }
	else
	proc { @@n-=1 }
	end
	end
	end

	first_counter = Counter.create_counter
	puts "first_counter.call #{first_counter.call}"
	puts "first_counter.call #{first_counter.call}"

	second_counter = Counter.create_counter
	puts "second_counter.call #{second_counter.call}"
	puts "first_counter.call #{first_counter.call}"
	puts "second_counter.call #{second_counter.call}"
	puts "first_counter.call #{first_counter.call}"