Variables and scope

Ruby
1

Hi all,

I would be asking my instructor this question be she is not available
on
the weekends…

How do I make “n” available from anywhere inside the class? I need to
keep the values in n from call to call.

When calling the method “pt”, “n” acts as if it was not declared above.

I get -1 instead of what I wish for … 99.

Thanks in advance,

Mike

class Test
n=100

def pt
puts “hi there”
n=-1
end

end

t = Test.new
puts t.pt

2

take note of the usage of @ for scope as well as the special
initialize method used as a constructor for the object.

also note note you common bug/mistake. Your where setting n to
negative one. you need to use n = n + -1 or shorthand version below is
n += -1

class Test
def initialize
@n = 100
end

def pt
p “hi there”
@n += -1
end
end

t = Test.new
puts t.pt

If you would like to know more have a look at attr_* in ruby

Good luck with your classes

~Stu

3

You are getting a -1 because you are using local variables. Thus, the n
within your def is not the same as the n within your class.
Since you declared n to be -1 in your def, that is what your program
responded with, a -1.
You need to initialize an instance variable that will be available
throughout the class.

You can also make your code more utilitarian with a parameter value that
can be changed any time you create a new instance.
Try the following:

class Test

def initialize(n)
@n = n
end

def pt
puts “hi there”
@n -= 1
end
end

t = Test.new(100)
puts t.pt

This way, you are not tied down to the value 100, but can use any value
you want.
I am new at this game and just taking the baby steps, but this seemed to
work.

Lauren