Slight confusion on how to set var

DRMorrisonDRMorrison Posts: 81
edited October 4 in Propeller 1 Vote Up0Vote Down
I am having a slight issue with setting a var in my main program from and object. I would like to change the var X from within
an object to affect the X var in the main program. I need to use another cog to change the var X, and then when the main program
uses it during its next iteration, it will see the new value that has been changed by the object. I think I need to use the @ symbol somehow,
but I don't fully understand the syntax. Do I simply write @X in the object?

Thanks, Daniel
(the issue is my lack of understanding, or ignorance. I've tried reading about it, but I just don't grasp it quite well enough.)

Comments

  • 7 Comments sorted by Date Added Votes
  • You have to pass the address of the variable in your main program to your object. Your object is going to have some sort of initialization method like:
    pub start(a,b,c)
       ... stuff ...
    
    You need to have another parameter like:
    var long addr    { place to save passed address }
    pub start(a,b,c,d)
        addr := d   { save the address passed in }
    
    Wherever you want to change the variable, you'd use the following. If the variable is a byte or word, you'd use BYTE() or WORD() instead of LONG():
    LONG(addr) := value
    
    In the main program, you'd pass the address of the variable like this:
    start(5, 10, 103, @variable)
    
  • DRMorrisonDRMorrison Posts: 81
    edited October 4 Vote Up0Vote Down
    So, object looks like...
    PUB start(@X)
     WORD(X) := y + z
    
    And then the main program would see the new value the next time it went to use it?
    Do I have to call the object from main, or will the value just change from within the object due to
    internal processing within the object?
  • DRMorrisonDRMorrison Posts: 81
    edited October 4 Vote Up0Vote Down
    I think I may have this...
    MAIN PROGRAM:
    VAR WORD X
    
    OBJ newX: "Xchanger"
    
    PUB Main
    
     newX.Start(@X)
    
    OBJECT Xchanger:
    VAR WORD Xadd
    
    PUB Start(X)
     Xadd := X
    
    PUB xchange
    
     WORD(Xadd) := {some new value based upon an input etc.}
    

    Does this look correct?
    Daniel
  • yes

    Mike
    I am just another Code Monkey.

    A determined coder can write COBOL programs in any language. -- Author unknown.

    The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this post are to be interpreted as described in RFC 2119.
  • The line:
    WORD(Xadd) won't compile, but this will: WORD[Xadd]
    I'm using BST

    Daniel
  • Sorry. I got carried away with the parentheses. It indeed is WORD[Xadd]. Looks good.
  • Thanks to everyone, Daniel
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