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difficulty in understanding the code from sklanguser page 372 - 382

Adhil
Hi Please refer the code taken from sklanguser( cadence skill language user guide ) page 377 - 382. i understand how to use classes, but i dont understand this code. defmethod( Update (( obj IntersectionTwoLines_Point )) printf( "Figure out my x & y from Lines %L %L\n" obj->L1 obj->L2 ) let(( A1 B1 C1 A2 B2 C2 det ) A1 = obj->L1->A B1 = obj->L1->B C1 = obj->L1->C A2 = obj->L2->A B2 = obj->L2->B C2 = obj->L2->C det = A1*B2-A2*B2 when( det == 0 error( "Can not intersect two parallel lines\n") ) obj->x = ((-C1)*B2-(-C2)*B1)*1.0/det obj->y = (A1*(-C1)-A2*(-C1))*1.0/det ) callNextMethod( obj ) ) where the A B & C are clearly variables of the class Line. they cannot be accessed by IntersectionTwoLines_Point which is a subclass of "Point" a sibling class of "Line" (refer the pages i sent you you will understand). how is A1 = obj->L1->A B1 = obj->L1->B C1 = obj->L1->C A2 = obj->L2->A B2 = obj->L2->B C2 = obj->L2->C possible? Adhil
  • Andrew Beckett

    Adhil,

    A little hard to read due to the formatting (perhaps you were using Chrome - this forum doesn't seem to work very well with Chrome).

    Anyway, the answer is in the function make_IntersectionTwoLines_Point(). This is an argument that takes two line objects, and creates an instance of the IntersectionTwoLines_Point class, with L1 and L2 set to the two line objects. Each line object is of class Line or one of its subclasses, and so have slots A, B and C. Thus the newly created object from this function has obj->L1->A etc.

    Hope that clarifies things.

    Andrew.

     

  • Adhil

    Hi Andrew,

    ok here is IntersectionTwoLines_ Point

    defclass( IntersectionTwoLines_Point ( Point )

    (

    ( L1  @initarg  L1)
    ( L2  @initarg  L2)

    ))

    this is the Line class

    defclass( ( GeometricObject ) 

    (

    ( A )
    ( B )
    ( C )

    ))

    therefore how do the two slots in IntersectionTwoLines_Point store the lines?

     

  • Andrew Beckett
    As I said in my last reply, look in the function make_IntersectionTwoLines_Point(). This creates an instance of the object and fills in the L1 and L2 slots with the two line objects, and each of these has an A, B and C slot.

    Andrew
  • Adhil

    Hi Andrew

     I just tested it out.... I  get it thanks alot!!

     Adhil

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