DSP Robotics Support

A little while ago I was a bit surprised to find out that variable states in DSP code blocks persist from one step to the next and aren't initialized every time the code runs through.

Now I'm wondering how this works with Ruby. Specifically working with arrays right now but I'd like to understand just in general. The manual states that the values stored on the inputs and outputs are persistent, but I'm talking about local variables defined within the code. From what I read you can define "events" that will prevent the code block from re-executing code outside of the events, so do you need to utilize this to keep things from re-initializing every time new input is received? Or is that unnecessary, or perhaps there's a different way about it? ...or is it not possible? I really don't know haha.

Hoping it's a simple question to answer. Thanks.

in ruby there are two kinds of variables: local which are colored black and global which are written with @ at the beginning and are colored gold. Actually, @ins and @outs are simply global variables that bridge FS and ruby (they are readable or writable from both).
local variables are specific to a method. You may have several local variables with the same name as long as they are in different methods (in case you don't know, you can initialize your own methods in similar fashion to functions in C). Global variables are simply global. They are accessible from all methods within the ruby component and keep their value until you change it or reload the schematic. You initialize them in the same way like local variables - simply by assigning value to them.
Look at the example in the manual at page 143. There is a sample and hold recreation in ruby that uses global variable "@last" to store the value between events.

KG_is_back wrote:You initialize them in the same way like local variables - simply by assigning value to them.

But what if you want to use the variable in a conditional, but don't want to reset the value at every step? The variable needs to be initialized before the conditional, but by assigning a value to it you're overwriting it.

just define a new Class or Module and assign an constant variable like:
MYCONSTVARIABLE = value

Can you give me an example of that in syntax?

For example say I want to do this (just random):


and I want @Array to be persistent.

What you mean with "persitent" ?

Define your variable in the init function and do your processing in the event function.

Tronic wrote:What you mean with "persitent" ?

I want the values to persist every time the code is run through (when an input is received), without being reset (when they're initialized).

TheOm wrote:Define your variable in the init function and do your processing in the event function.

Ok, so I should use the event function. Again would you mind giving me an example of this in syntax I can look at? It's hard to pull up specific things like this searching documentation.

ok, just initialize an
@@my_global_class_variable
so you ca use it in any other class instance, without initialize it every time.

def init
@@my_global_class_array = new Array[size]
# function to populate array
end

OR

this is only available in current class declaration

def init
@my_local_class_array = new Array[size]
# function to populate array
end

Full Example: