Re: First attribute on Enumerated types

[David Starner <dstarner98@aasaa.ofe.org>]

"James S. Rogers" wrote:
> 
> David,
> 
> I suspect that, in your case, Color is a variable, and not a subtype name.
> The 'First attribute works for an enumeration type, not a variable of an
> enumeration type.
> 
> Jim Rogers
> Colorado Springs, Colorado
> 
> -----Original Message-----
> From: David Starner <dstarner98@aasaa.ofe.org>> 
> >I'm trying to compile a program that refers to Color'First, and GNAT
> >gives an error that
> >tree.ads:12:91: prefix for "First" attribute must be array
> >According to the Ada book at hand, First is a valid attribute for
> >enumerated types. What am I doing wrong? How do I get the first item in
> >an enumerated list?

Since I quickly composed the first message, here's the actual code.
Color is definitely a type. It should be enumerated - is there any
way to tell the compiler that? In retrospect, that's probably my error.

with Lists;
generic 
    type Node_type is private;
    type Color is private; 
package Tree is
    type Tree is limited private;
    type Node_Pointer is access Node_type;
    type TreePointer is access Tree;
    
    package Tree_List is new Lists(TreePointer, Natural); 
    
    procedure SetRoot(BaseTree: in out Tree; Item: in Node_Pointer;
NewColor: in Color := Color'First);
    procedure AddChild(BaseTree: in out Tree; Child: in TreePointer);
    procedure RemoveChild(BaseTree: in out Tree; Child: in integer);
--  procedure RemoveChild(BaseTree: in out Tree; Child: in out
Tree_List.Pointer);   
    function GetRootData (BaseTree: in Tree) return Node_type;
    procedure SetColor (BaseTree: in out Tree; NewColor: in Color);
private
    type Tree is 
        record 
            Data: Node_Pointer;
	    NodeColor: Color;
            Children: Tree_List.List;
        end record;
end Tree;

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