As you can see, I pass in var1 into the method and then I change the
value to 'test1'. I would like to method to go back and update var1,
so that if passed into another method it reflects the change that
method change var_in did. Does this make since? Im new to
programming.
As you can see, I pass in var1 into the method and then I change the
value to 'test1'. I would like to method to go back and update var1,
so that if passed into another method it reflects the change that
method change var_in did. Does this make since? Im new to
programming.
#--- @var1 = "test"
puts @var1
def change @var1 = "test1"
end
change
puts @var1 #---
or, if you want to pass the value into your method:
#---
def change(value) @var1 = value
end
change 'something'
puts @var1 #---
You'll want to pick up a basic understanding of scoping, data
encapsulation, and object oriented design. You might start with some
simple tutorials that help you learn by example, such as TryRuby: http://tryruby.hobix.com/
The first edition of Programming Ruby is also available free online,
and is a good book. Once you get somewhat familiar, you might want to
pick up the second edition as a reference
As you can see, I pass in var1 into the method and then I change the
value to 'test1'. I would like to method to go back and update var1,
so that if passed into another method it reflects the change that
method change var_in did. Does this make since? Im new to
programming.
As you can see, I pass in var1 into the method and then I change the
value to 'test1'.
No. You pass the value of "var1" in, i.e. the object which "var1" refers to. In passing in that value it is assigned to "var_in". Now you have two variables referring the same object. Then you make "var_in" point to another object (your string 'test1'). But "var1" in the other scope still points to the original value / object.
I would like to method to go back and update var1,
so that if passed into another method it reflects the change that
method change var_in did. Does this make since? Im new to
programming.
It may make sense and you can actually do such things in other programming languages. I have never felt the need to do this in Ruby so you definitively can live without this feature. There are a number of options you have, two of them have been mentioned in this thread (assignment of the return value, instance variables). Which of those is the most appropriate depends on the problem you are trying to solve. At the moment this looks like a solution looking for a problem.
As you can see, I pass in var1 into the method and then I change the
value to 'test1'. I would like to method to go back and update var1,
so that if passed into another method it reflects the change that
method change var_in did. Does this make since? Im new to
programming.
What you want to do is a "call by reference".
What you get is a "call by value".
This is just to let you know the terminology.
Search the web for more about these concepts.
As soon as you assign a new value (object) to
your local variable in the method change(), it
will no longer point to the object passed as
argument, but instead point to a new object.
The object that was passed remains unchanged.
The code below my signature could make a lot
of things clearer. Just run it and come back
if you have questions.
Btw: You don't need to know all this to use
Ruby. So don't worry and don't forget to have
fun with this wonderful and easy programming
language.
HM
def change x
puts "With value just passed:",
"ID of x: #{x.object_id}",
"Value of x: #{x}"
x = 'abc'
puts "With new value: ",
"ID of x: #{x.object_id}",
"Value of x: #{x}"
return x
end
a = "Hallo"
puts "Before calling change():",
"ID of a: #{a.object_id}"
rv = change a # return value
puts "After calling change():",
"ID of rv: #{rv.object_id}",
"Value of rv: #{rv}",
"ID of a: #{a.object_id}",
"Value of a: #{a}"
