Re: Assistance on extending a private record from a private record with a generic attribute...

[nobody@REPLAY.COM (Anonymous)]

<35364E81.94B51B0F@amherst.com>

On Thu, 16 Apr 1998 21:26:10 GMT, stt@houdini.camb.inmet.com (Tucker
Taft) wrote:

> Christopher Campise (crc@amherst.com) wrote:
> 
> : Ada95 on a Rational Apex compiler:
> : I have a "superclass" with a private record consisiting of a generic
> : type attribute.  I need to inherit this from within another package but
> : am receiving compiler errors stating that "a record extension will be
> : provided iff the parent record is tagged," (which it is).  Is this even
> : legal?  I looked everywhere for examples and found none that relate to
> : this, adahome.com, Programming in Ada95, Rendezvous with Ada95, plus
> : other tutorials.  Any ideas?
> 
> You cannot select items from a generic package.  You must
> first instantiate the generic package, and select items from
> the instance.  
> 
> : For example:
> 
> : ***********
> : generic
> :    type Value_Class is private;
> 
> : package Generic is
> :    type Class is tagged private;
> ...

Surprisingly, even Tucker Taft did not point out that you cannot have a
package named Generic. "generic" is a reserved word.

Assuming that you change the name, perhaps to Generic_Class, then you
still don't have a package, so you can't refer to its type Class. You
need to instantiate the generic:

package My_Class is new Generic_Class (Value_Class => My_Type);

Now you have a package named My_Class, and may refer to My_Class.Class.

Jeff Carter  PGP:1024/440FBE21
My real e-mail address: ( carter @ innocon . com )
"Son of a window-dresser."
Monty Python & the Holy Grail

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