-- File:	TDesignVariable_Variable.cdl
-- Created:	Wed Dec 10 10:37:50 1997
-- Author:	Denis PASCAL
--		<dp@dingox.paris1.matra-dtv.fr>
---Copyright:	 Matra Datavision 1997


class Variable from TDataStd inherits Attribute from TDF

    ---Purpose: Variable attribute. 
    --          ==================  
    --          
    --           * A variable is  associated to a TDataStd_Real (which
    --          contains its    current  value) and  a   TDataStd_Name
    --          attribute (which  contains  its name).  It  contains a
    --          constant flag, and a Unit
    --           
    --          * An  expression may  be assigned  to a variable.   In
    --          thatcase the expression  is handled by the  associated
    --          Expression Attribute  and the Variable returns True to
    --          the method <IsAssigned>.


uses Attribute         from TDF,
     Label             from TDF,
     ExtendedString    from TCollection,
     Real              from TDataStd,
     Expression        from TDataStd,
     GUID              from Standard,
     Real              from Standard,  
     RealEnum          from TDataStd,
     DataSet           from TDF,
     RelocationTable   from TDF,
     AsciiString       from TCollection
     

is

    ---Purpose: class methods
    --          =============

    GetID (myclass)    
    	---C++: return const & 
    returns GUID from Standard;

    Set (myclass ; label : Label from TDF)
    ---Purpose: Find, or create, a  Variable attribute.
    returns Variable from TDataStd;
    
    ---Purpose: Real methods
    --          ============

    Create
    returns mutable Variable from TDataStd;

    Name (me : mutable; string : ExtendedString from TCollection);
    ---Purpose:  set or change the name  of the variable, in myUnknown
    --           and my associated Name attribute.

    Name (me)
    returns ExtendedString from TCollection;
    ---Purpose: returns    string   stored  in   the  associated  Name
    --          attribute.
    ---C++: return const &  

    Set (me; value : Real from Standard; dimension : RealEnum from TDataStd = TDataStd_SCALAR);
    ---Purpose: retrieve or create  the associated real attribute  and
    --          set the  value  <value>.   if creation, dimension   is
    --          written.

    IsValued (me)
    ---Purpose: returns True if a Real attribute is associated.
    returns Boolean from Standard; 
    
    Get (me)
    ---Purpose: returns value stored in associated Real attribute.
    returns Real from Standard;

    Real (me)
    ---Purpose: returns associated Real attribute.
    returns Real from TDataStd;      

    IsAssigned (me) returns Boolean;
    ---Purpose: returns True if an Expression attribute is associated.    

	--    Assign (me; E : GeneralExpression from Expr)
    ---Purpose: create(if doesn't exist), set and returns the assigned
    --          expression attribute.
    --returns Expression from TDataStd;    
    
    Assign (me)
    ---Purpose: create(if  doesn't exist)  and  returns  the  assigned
    --           expression  attribute. fill it after.
    returns Expression from TDataStd;

    Desassign (me);
    ---Purpose: if <me> is  assigned delete the associated  expression
    --          attribute.

    Expression (me)
    ---Purpose: if <me>  is  assigned, returns  associated  Expression
    --          attribute.
    returns Expression from TDataStd;
    
    IsCaptured (me) returns Boolean;
    ---Purpose: shortcut for <Real()->IsCaptured()>

    IsConstant (me)
    ---Purpose: A constant value is not modified by regeneration.
    returns Boolean from Standard;
    
    Unit (me:mutable; unit : AsciiString from TCollection);
    
    Unit (me)
    ---C++: return const &
    returns AsciiString from TCollection;
    
    ---Purpose: to read/write fields
    --          ===================

    Constant (me : mutable; status : Boolean from Standard);
    ---Purpose:  if  <status> is   True, this  variable  will not   be
    --          modified by the solver.
    
    ---Category: TDF_Attribute methods
    --           =====================
    
    ID (me) 
    ---C++: return const &  
    returns GUID from Standard;

    Restore (me: mutable; With : Attribute from TDF);

    NewEmpty(me)
    returns mutable Attribute from TDF;

    Paste (me; Into : mutable Attribute from TDF;
	       RT   : mutable RelocationTable from TDF);    
  
    References (me; DS : DataSet from TDF)
    ---Purpose: to export reference to the associated Name attribute.
    is redefined;
  
    Dump(me; anOS : in out OStream from Standard)
    returns OStream from Standard
    is redefined;
    ---C++: return &

fields

    isConstant : Boolean      from Standard;
    myUnit     : AsciiString  from TCollection;

end Variable;