Having problems with my instance variable

I’m sorry if this question seem stupid, but couldn’t find it in the
books.

I have this code in the models directory:
class Figure
attr_reader :xpos, :ypos

def initialize
@xpos = 0
@ypos = 0
@other = 0
@another = 0
end

def some
call_other(@xpos,@ypos)
end

def more
call_other(@other,@another)
end

def call_other(var1, var2)
max = 9
var1= rand(max)
var2=rand(max)
end
end

And have this on my controller:

def figure
fig = Figure.new
fig.some
render :text => “

new values

”+fig.xpos.to_s+"
"+fig.ypos.to_s
end

Problem is, it always print 0 0… as if the random wouldn’t work, but I
have test the random outside this method (calling it in the first
method,
not the second one), but the second method is one I need cos I use it
too
many times and with different instance variables

Any help?

On Feb 4, 2008 8:14 PM, macaco [email protected] wrote:

var1= rand(max)
var2=rand(max)
end
end

It’s not clear to me what you’re trying to do here. You want a method
that
will set arbitrary variables to random numbers? That’s a wild guess.
What
you’re actually doing when you call call_other is passing it the values
in
@xpos and @ypos (which is 0 and 0 initially). Then, in call_other,
you’re
taking those 0s in with var1 and var2. Then you’re over-writing var1 and
var2 with random numbers (0s are lost, as far as this method is
concerned)
and then… you exit. You’re leaving your @vars untouched because you’re
passing the values, not the variables themselves.

If “max” is always going to be the same, I’d make it a constant at the
class
level and then just have some look like this:

def some
@xpos = rand MAX
@ypos = rand MAX
end

If max won’t be the same all the time, make a method that figures it out
and
returns a random number based on it… An example will make more sense,
maybe.

def some
@xpos = generate_random
@ypos = generate_random
end

def generate_random
max = 9 # or whatever determines your max value
rand(max)
end

I hope that’s clear. Scope can be confusing sometimes. If I am too
rambly (I
hear that a lot), maybe someone with more experience will be more clear,
too.

Ben

def some
call_other(@xpos,@ypos)
end

def more
call_other(@other,@another)
end

This worked:
class Test
attr_reader :xpos

def initialize
@xpos = 0
end

def some
p “before call: #{@xpos}”
#notice the colon
c :@xpos
p “after call: #{@xpos}”
end

def call_other(var)
max = 9
self.instance_variable_set(var, rand(max))
end
end

begin
t = Test.new
t.some
end

[email protected] ~ $ ruby test.rb
“before call: 0”
“after call: 7”

[email protected] ~ $ ruby test.rb
“before call: 0”
“after call: 2”

Warning: I’m not feeling well and the NyQuil is kicking in… :confused:

Thanks Day, but this is just a simplification of what I need

@Andrew S., thanks instance_variable_set makes it’s work, but what if
i
need the data inside too… for example

def call_other(var1,var2)
max = 8
if(var1 == 0)
var1 = rand max
else
var1 += max
end
var2 = rand max
end

BTW, can you explain the line of code “c :@xpos”, didn’t get it

Thanks again

On Feb 5, 2008 11:37 AM, macaco [email protected] wrote:

@Andrew S., thanks instance_variable_set makes it’s work, but what if i
need the data inside too…

I think instance_variable_get? Check out http://www.ruby-doc.org/core/
and
look in the right column for methods that start with instance_v. Or do a
find on _variable and see what turns up.

Ben

This forum is not affiliated to the Ruby language, Ruby on Rails framework, nor any Ruby applications discussed here.

| Privacy Policy | Terms of Service | Remote Ruby Jobs