Help invoking a method of a class

Ruby
1

I started playing with classes and to that effect, I put this simple
do-nothing class just to make sure I can invoke a method within a class.

class Test
def mag(size)
maxLoop = size * size
r1 = Array.new(size) {1}
p r1
end # End method mag
end # End class

mag.Test 9

I am getting this error:

C:$user\ruby\Programs\DejaVou>ruby Test.rb
Test.rb:9: undefined local variable or method `mag’ for main:Object
(NameError)

Any ideas anyone?
I am sure it is something trivial, but, trivial or not I can’t get it.

Thank you

Victor

2

Victor R. wrote:

I started playing with classes and to that effect, I put this simple
do-nothing class just to make sure I can invoke a method within a class.

class Test
def mag(size)
maxLoop = size * size
r1 = Array.new(size) {1}
p r1
end # End method mag
end # End class

mag.Test 9

I am getting this error:

C:$user\ruby\Programs\DejaVou>ruby Test.rb
Test.rb:9: undefined local variable or method `mag’ for main:Object
(NameError)

Any ideas anyone?
I am sure it is something trivial, but, trivial or not I can’t get it.

You need to create an object of the class, and then use the object to
call the method:

class Test
def mag(size)
r1 = Array.new(size)
p r1
end
end

my_obj = Test.new()
my_obj.mag 10

Or, you can create a ‘class method’, which allows you to call the method
with the class name:

class Dog
def Dog.bark
puts “Woof! woof!”
end
end

Dog.bark

3

On Nov 2, 2007, at 2:07 PM, Victor R. wrote:

end # End class
Any ideas anyone?
first, you’re defining a instance method
second, the convention to call a method in ruby is: receiver.method,
so in this case, you should call the method like this:

Test.mag 9

although, this won’t work either, because the method mag is an
instance method, so you should first create an instance, with ‘new’:

Test.new.mag 9

Anyway, at this point, I would suggest you to read something in
Object Oriented Programming… I think a lot of good pointers have
been suggested here in the list before, so make sure you check the
archives.

I am sure it is something trivial, but, trivial or not I can’t get it.

Thank you

Victor

regards,

4

Jeremy W. wrote:

I think your going to get an undefined method error even after doing
t = Test.new
t.mag 10

you have Array.new(size) {l} <–what is l?

arr = Array.new(3) {1}
p arr

–output:–
[1, 1, 1]

5

Thank you all for your help.

I agree, I really need to understand OOP.

Thanks again

Victor

6

I think your going to get an undefined method error even after doing
t = Test.new
t.mag 10

you have Array.new(size) {l} <–what is l?

7

On 11/2/07, 7stud – [email protected] wrote:

–output:–
[1, 1, 1]

I am not sure that helps if the posters | (pipe), 1 (one), l
(lowercase L) and I (uppercase i) looks all alike;)
Long live Serif Fonts!!!

HTH
Robert

8

Oh, yes:
Array.new(size) {l} <–what is l?
That is number 1, the char between {}. It actually populates the array
with
ones (1).

Thank you

Victor

9

7stud – wrote:

Jeremy W. wrote:

I think your going to get an undefined method error even after doing
t = Test.new
t.mag 10

you have Array.new(size) {l} <–what is l?

arr = Array.new(3) {1}
p arr

–output:–
[1, 1, 1]

OHHHH, that’s the number one, I thought it was the letter L :slight_smile:
oops, my bad.

~Jeremy

10

I can do it now if you like (I just wasn’t sure about how long your
meeting would be).